Oman e-invoicing rules, explained one by one

The invoice's 'Specification identifier' does not start with 'urn:peppol:pint:billing-1@om-1'. This value tells receiving systems the invoice was built to the Oman PINT rules specifically - using a generic or wrong-country value here will get it rejected as not being an Oman invoice.

The 'Business process' field must read exactly 'urn:peppol:bis:billing'. If it is missing or different, the invoice does not declare which Peppol business process it belongs to.

The file is not a UBL Invoice or CreditNote document (or the XML namespaces have been changed). This usually means the wrong file was uploaded, or the XML was edited by hand and a namespace got broken.

The invoice is missing its 'Specification identifier' - the field that says which exact invoicing standard it was built against. This is normally filled in automatically by invoicing software.

A date field is not in the required YYYY-MM-DD format.

The invoice must state a business process type code.

A time value on the invoice is not in the required hh:mm:ss format (fractional seconds and a time zone are optional).

The import date is not a valid date in YYYY-MM-DD format.

A date field on the invoice is not in the required YYYY-MM-DD format.

The invoice's specification identifier (the code identifying which invoice format is used) contains a wildcard character such as '*', which is not allowed.

The credit note or debit note reason code must be one of the standard codes (for example cancellation, or a correction to value, quantity, or VAT) - a code outside this list is not valid.

A line or breakdown is marked VAT-exempt ('E') but its exemption reason code is not one of the official Oman exemption codes (VATEX-OM-01 through VATEX-OM-12).

The item type code must show whether the line is goods or services - only 'G' (goods) or 'S' (services) is valid.

The item's HS (customs classification) code must be a valid 12-digit Oman HS code. A 6-digit ISIC code does not belong in this field - it goes in the separate industrial classification field.

The industrial classification code must be a valid 6-digit ISIC code from the Oman Ministry of Commerce's activity list. An HS (customs/goods) code does not belong in this field - it goes in the separate item classification field.

The Incoterms code must be one of the standard international trade terms (for example EXW, FOB, CIF or DDP) - a code outside this list is not valid.

Wherever the zero-rated VAT category is used (on a line, discount, charge or VAT breakdown), the reason code must be one of the official zero-rating codes (VATZR-OM-01 to VATZR-OM-16). If the supply is not actually zero-rated, correct the VAT category instead.

On a profit-margin invoice (self-invoice or regular), the relevant item must carry a profit-margin reason code from the official list.

The service classification code must be one of the standard service-type codes from the official list - a code outside this list is not valid.

When an item classification code is given, its scheme must be marked 'HS' (for goods) or 'MP' (for services) - an ISIC code belongs in a separate field, not here.

The seller's electronic address must state which identification scheme it uses, not just the number itself.

The buyer's electronic address (used to route the invoice electronically) must state which identification scheme it uses, not just the number itself.

An invoice line for goods is missing its HS (customs) classification code; this is required unless the invoice is a simplified tax invoice.

The HS (customs) classification code is not exactly 12 digits — Oman HS codes must be 12 digits long.

An invoice line is missing its industrial classification (ISIC) code. This is required on most invoices, but not on simplified tax invoices, imports of goods, imports of services, or profit-margin self-invoices.

For an import-of-goods invoice, the import date, customs declaration number, and Incoterms must all be provided.

The unit of measure used for the price's base quantity must match the unit of measure used for the invoiced quantity.

For a profit-margin invoice, an item's HS classification code cannot start with 7101, 7102, 7103, 7104, 01, or 06.

For an invoice marked as a special-zone supply, both the buyer's and the seller's Oman subdivision codes must be provided.

For an invoice line for goods, the HS classification code must be taken from the Harmonized System code list published by the Royal Oman Police (Directorate General of Customs).

The invoice/credit-note type code is not one of the standard UNTDID 1001 codes Peppol recognises (e.g. 388 for a standard invoice).

The coding scheme used to identify a referenced object on the invoice is not one of the allowed UNTDID 1153 codes.

The coding scheme used for a party's identification number on the invoice is not one of the allowed ISO 6523 codes.

The coding scheme used for a legal registration number (seller, buyer, or another party) is not one of the allowed ISO 6523 codes.

The unit-of-measure code for a quantity is not one of the allowed UN/ECE Recommendation 20/21 codes.

A document-level discount must include either both its base amount and percentage, or neither of them - not just one.

A document-level charge must include either both its base amount and percentage, or neither of them - not just one.

If any invoice line, discount or charge is marked VAT-exempt, the invoice must include exactly one VAT breakdown for the exempt category (this breakdown is optional on a simplified tax invoice).

For the VAT-exempt breakdown, the taxable amount must equal the total net amount of the exempt invoice lines, minus any exempt discounts and plus any exempt charges. This amount is not required on a simplified tax invoice.

If any invoice line, discount or charge is marked as out of VAT scope, the invoice must include exactly one VAT breakdown for that category (this breakdown is optional on a simplified tax invoice).

For the out-of-scope VAT breakdown, the taxable amount must equal the total net amount of the out-of-scope invoice lines, minus any out-of-scope discounts and plus any out-of-scope charges. This amount is not required on a simplified tax invoice.

At least one invoice line, allowance or charge is marked as standard-rate VAT ('S'), but the invoice's VAT summary does not contain a matching standard-rate breakdown group.

For the standard VAT rate, the taxable amount shown in the VAT summary does not match the sum of the invoice lines (plus charges, minus allowances) that actually carry that rate. This is almost always a manual totalling mistake.

For the standard VAT rate, the VAT amount shown does not equal the sum of the line-level VAT amounts (plus charge VAT, minus allowance VAT) for that rate. Check the arithmetic on the invoice lines that use standard-rate VAT.

The standard-rate VAT total is off by a tiny rounding amount (within the permitted Baisa tolerance). This is ACCEPTED, not a failure - it is shown so you can confirm the rounding was intentional.

If any invoice line, discount or charge is marked zero-rated, the invoice must include exactly one VAT breakdown for that category (this breakdown is optional on a simplified tax invoice).

For the zero-rated VAT breakdown, the taxable amount must equal the total net amount of the zero-rated invoice lines, minus any zero-rated discounts and plus any zero-rated charges. This amount is not required on a simplified tax invoice.

A VAT category code somewhere on the invoice is not one of the allowed Oman codes: S (standard 5%), Z (zero-rated), E (exempt) or O (not subject to VAT).

A document-level allowance (discount) must state its amount.

Each document-level allowance (discount) must include a reason for it, either as text or as a code.

Where a discount has both a base amount and a percentage, the discount amount must equal the base amount multiplied by the percentage, divided by 100.

If a discount or charge on an invoice line has a percentage, it must also have a base amount.

A document-level charge must state its amount.

Each document-level charge must include a reason for it, either as text or as a code.

Each invoice line allowance (discount) must state its amount.

If a document-level discount or charge has a percentage, it must also have a base amount.

Each invoice line allowance (discount) must include a reason for it, either as text or as a code.

A document-level charge must include a reason code for the charge.

Each invoice line charge must state its amount.

Each invoice line charge must include a reason for it, either as text or as a code.

A document-level discount marked as standard-rated VAT must show a VAT rate of exactly 5%.

A document-level discount marked VAT-exempt or zero-rated must include a VAT exemption reason code.

Where a charge has both a base amount and a percentage, the charge amount must equal the base amount multiplied by the percentage, divided by 100.

A document-level charge marked as VAT-exempt or zero-rated is missing its VAT exemption reason code.

An invoice line's net amount does not equal quantity x unit price (adjusted for any line charges or allowances). Recheck the multiplication on that line.

A discount or charge on an invoice line gives only one of its base amount and percentage - both must be given together, or neither.

Each discount or charge entry has an indicator marking it as a charge or a discount, and that indicator's value must be exactly 'true' or 'false'.

A document-level allowance marked as VAT-exempt has a VAT rate entered, but exempt allowances must not have one.

A document-level allowance marked as out-of-scope has a VAT rate entered, but out-of-scope allowances must not have one.

A document-level allowance marked as zero-rated must have its VAT rate set to 0.

A document-level allowance (discount) amount has more than 2 decimal places.

A document-level charge amount has more than 2 decimal places.

The coded reason given for a discount is not one of the allowed UNCL 5189 codes.

The coded reason given for an extra charge is not one of the allowed UNCL 7161 codes.

The invoice's stated total of document-level allowances (discounts) does not equal the sum of the individual allowance amounts listed.

The invoice's stated total of document-level charges does not equal the sum of the individual charge amounts listed.

The 'total before VAT' does not equal (sum of line net amounts) minus (allowances) plus (charges). Recheck this subtotal.

The reason given for a discount appears more than once for the same discount; it may only appear once.

The reason given for an extra charge appears more than once for the same charge; it may only appear once.

The VAT exemption reason given for a discount or charge appears more than once; it may only appear once.

The invoice does not state the sum of all invoice-line net amounts - a required subtotal field.

For a profit-margin invoice or profit-margin self-invoice, the total amount due is missing or does not equal the sum of the line totals including VAT.

An amount or quantity on the invoice is negative where it is not allowed to be. Only the rounding amount is permitted to be negative.

The invoice's 'Total including VAT' does not equal the net amount plus the VAT amount. Recheck the final total.

For a profit-margin invoice, the total amount due must be shown in Omani Rial (OMR).

The invoice's stated 'sum of line net amounts' does not equal the actual sum of all the invoice lines' net amounts. This is almost always a manual totalling error.

The invoice's total VAT amount does not equal the sum of the VAT amounts in each VAT breakdown group.

The final 'amount due for payment' does not equal (total including VAT) minus (amount already paid) plus (rounding amount).

An amount on the invoice has too many decimal places. Regular amounts may have at most 3 decimal places, and the currency exchange rate may have at most 7.

On an export invoice for the re-export of goods, both the supporting document reference and its UUID must be provided.

A credit note or debit note must reference the original invoice by number, issue date, and UUID - all three must be provided.

Each additional supporting document listed on the invoice must include a reference (an identifier) for that document.

If the invoice refers to a preceding invoice, that reference must include the earlier invoice's number.

An additional-document entry on the invoice should not contain both a reference to the invoiced object and an attached file at the same time.

An additional-document entry on the invoice must not contain both a reference to the invoiced object and a document description at the same time.

The invoice can include at most one invoiced-object identifier at the document level.

Each invoice line can include at most one invoiced-object identifier.

The invoice can include at most one project reference.

The invoice can include at most one contract reference.

The invoice can include at most one receiving-advice reference.

The invoice can include at most one despatch-advice reference.

A profit-margin invoice is missing a reference to a preceding invoice, or that reference is missing its UUID — both the reference and the UUID are required.

A reference to a preceding invoice appears more than once within the same billing reference; it may only appear once.

A reference to a preceding invoice is given without that invoice's number; the number must be included.

The description of a supporting document appears more than once for the same document; it may only appear once.

The project reference appears more than once; it may only appear once on the invoice.

The tender or lot reference appears more than once; it may only appear once on the invoice.

Each payment instruction must specify a payment means type code (how the payment is made, for example bank transfer).

If the invoice shows a prepaid amount, it must also reference the prepayment invoice's number and UUID.

An invoice can include at most one payment card account.

An invoice can include at most one payment mandate (direct-debit authorization).

A prepayment invoice cannot also be marked as a summary invoice, deemed supply, or profit-margin self-invoice — but this invoice combines them.

The payment method code is not one of the allowed UNCL 4461 codes.

The payment terms text appears more than once; it may only appear once on the invoice.

The text describing the payment method appears more than once for the same payment means entry; it may only appear once.

The direct-debit mandate reference appears more than once; it may only appear once.

The payment means text appears more than once for the same payment means entry; it may only appear once.

The payment instruction ID appears more than once; it may only appear once.

On an export invoice where the VAT exemption reason is 'export of service', the delivery country must not be Oman.

An export invoice must state the delivery country.

If the invoice gives both a start and an end date for the invoicing period, the end date must be on or after the start date.

On a summary invoice, the invoicing period's start and end dates must fall within the same calendar month.

A summary invoice or a continuous-supply invoice must state both the invoicing period's start and end dates.

An e-commerce supply invoice must include the full delivery address: address lines, city, postal code and country.

If a delivery address is given, it must include the destination country.

If an invoice line has its own period, that period's start date must fall within the invoice's overall period.

If an invoice line has its own period, that period's end date must fall within the invoice's overall period.

The invoice can include at most one invoicing period.

The delivery details (who the goods went to and where) appear more than once; they may only appear once on the invoice.

A country code on the invoice (seller, buyer, delivery, etc.) is not a valid ISO 3166-1 two-letter code (e.g. OM for Oman).

The coding scheme used for the delivery location's identifier is not one of the allowed ISO 6523 codes.

An invoicing period was given without a start date or an end date; at least one of the two must be filled in.

An extra address line for the delivery address appears more than once; it may only appear once.

The 'VAT accounting currency' must be OMR (Omani Rial). Oman requires the VAT amounts to always be reportable in Rial, even if the invoice itself is billed in a foreign currency.

Every VAT breakdown group on the invoice must state the taxable amount that VAT rate applies to. This is missing on at least one VAT group.

Every VAT breakdown group must state the actual VAT amount for that group. This is missing on at least one VAT group.

Every VAT breakdown group must be labelled with a VAT category code (Standard/Zero-rated/Exempt/Not subject). This label is missing on at least one group.

Every VAT breakdown group must state its VAT rate (percentage), unless the whole invoice is not subject to VAT. This is missing on at least one group.

An invoice line marked VAT-exempt must not have a VAT rate entered for it.

The VAT amount in the VAT-exempt breakdown must be zero. This amount is not required on a simplified tax invoice.

An invoice line marked as out of VAT scope must not have a VAT rate entered for it.

The VAT amount in the out-of-scope VAT breakdown must be zero. This amount is not required on a simplified tax invoice.

A line marked as standard-rate VAT ('S') has a VAT rate that is not 5%. Oman's standard VAT rate is 5% - any other percentage on a standard-rated line will fail this check.

A standard-rate ('S') VAT breakdown group also carries a VAT exemption reason - it should not, because standard-rated supplies are not exempt.

The seller's VAT number must not appear more than once on the invoice.

An invoice line marked zero-rated must show a VAT rate of exactly 0%.

The VAT amount in the zero-rated VAT breakdown must be zero. This amount is not required on a simplified tax invoice.

When a seller or buyer identifier other than the VAT number is given, its scheme code must be one of the standard codes (for example commercial registration, tax ID, civil ID, or passport number) - a code outside this list is not valid.

A VAT number (Seller, Buyer or Third-party) is not in the required Oman format: the letters 'OM' followed by exactly 10 digits, 12 characters total. Check for extra spaces, a missing 'OM' prefix, or too few/too many digits.

The invoice currency is not OMR, but no exchange rate to OMR is given. Any invoice in a foreign currency must also state the exchange rate used to convert to Rial.

When the invoice currency is not OMR, the exchange rate to OMR must not have more than 7 decimal places.

The Seller's VAT number is missing. It is mandatory on every invoice except three named transaction types: import of goods, import of services under reverse charge, and a profit-margin self-invoice.

Every tax scheme code on the invoice - for the seller, buyer, third party or a VAT category - must be 'VAT'. The seller must have exactly one, and the buyer may have only one.

The invoice does not state its total amount before VAT.

The invoice does not state its total amount including VAT.

On a third-party invoice, the third party's full details (name, VAT number, address, city, postal code and country) must all be provided, and only once - not missing and not duplicated.

Neither a Buyer identifier nor a Buyer VAT number is present. For most invoice types (full tax invoice, export, summary, etc.) at least one way to identify the buyer is mandatory.

For a self-billed invoice/credit note, import of services (reverse charge), profit-margin self-invoice, or import of goods, the buyer's VAT number must be provided.

Same requirement as above: an exchange rate to OMR is required whenever the invoice currency is not OMR.

Every invoice line must show its own VAT amount, unless the invoice is a simplified tax invoice.

An invoice line marked VAT-exempt must show a VAT amount of zero.

A document-level charge marked as standard-rated VAT must show a VAT rate of exactly 5%.

A VAT rate must be a plain number between 0 and 100 with at most 2 decimal places - do not include a percent sign.

If the invoice states a separate accounting currency for VAT, it must also give the total VAT amount in that currency.

In the VAT breakdown shown in the accounting currency, a standard-rated category must show a VAT rate of exactly 5%.

An invoice line marked 'not subject to VAT' must show a VAT amount of zero.

When an exchange rate is given, its source currency must match the invoice currency and its target currency must match the VAT accounting currency.

A VAT breakdown marked 'not subject to VAT' must not have a VAT rate entered for it.

For an invoice in a foreign currency where the VAT accounting currency is OMR, the total VAT amount in OMR is missing or does not equal the exchange rate multiplied by the invoice's total VAT amount.

For an invoice in a foreign currency that includes standard-rate VAT lines, the VAT breakdown is missing the amount, category, or rate shown in the accounting currency (OMR).

A VAT breakdown marked as VAT-exempt has a VAT rate entered, but exempt entries must not have a rate.

A VAT breakdown marked as VAT-exempt or zero-rated is missing its VAT exemption reason code.

A VAT breakdown marked as out-of-scope has a VAT exemption reason code entered, but out-of-scope entries must not have one.

An invoice line is missing its VAT category code.

An invoice line marked as zero-rated for VAT has a non-zero VAT amount; it must be zero.

The invoice's total VAT amount and its total VAT amount in the accounting currency must have the same sign (both positive or both negative).

For a profit-margin self-invoice, the item's VAT category must be 'outside the scope of VAT'.

In the VAT breakdown shown in the accounting currency, an entry marked as VAT-exempt has a VAT rate entered, but exempt entries must not have one.

In the VAT breakdown shown in the accounting currency, an entry marked as out-of-scope has a VAT rate entered, but out-of-scope entries must not have one.

In the VAT breakdown shown in the accounting currency, an entry marked as zero-rated must have its VAT rate set to 0.

A document-level charge marked as VAT-exempt has a VAT rate entered, but exempt charges must not have one.

A document-level charge marked as out-of-scope has a VAT rate entered, but out-of-scope charges must not have one.

A document-level charge marked as zero-rated must have its VAT rate set to 0.

The buyer's tax (VAT) number appears more than once; it may only appear once on the invoice.

The invoice total before VAT has more than 2 decimal places.

The invoice total VAT amount has more than 2 decimal places.

The invoice total including VAT has more than 2 decimal places.

The currency used for the VAT amounts in the accounting currency does not match the invoice's declared VAT accounting currency.

For an export invoice where the VAT exemption reason is 'export of service', a valid service-type code from the official services code list must be provided.

A line's VAT amount does not equal that line's VAT rate multiplied by its net amount. Recheck the VAT calculation on that specific line.

A line's VAT amount is off by a tiny rounding difference (within the permitted Baisa tolerance). This is ACCEPTED, not a failure - shown so you can confirm the rounding was intentional.

An exchange rate is entered, but the invoice currency is OMR, so the exchange rate must be removed.

The 'total including VAT' does not equal (total before VAT) plus (total VAT amount).

None of the Seller identifier, Seller legal registration number, or Seller VAT number is present - at least one is required so the buyer's system can automatically recognise the supplier.

The reason given for a VAT exemption appears more than once within the same VAT breakdown; it may only appear once.

The reason a line item is exempt from VAT appears more than once for the same line; it may only appear once.

The seller's tax registration details appear more than twice; they may appear at most twice.

The tax point date (when VAT becomes due) appears more than once; it may only appear once.

A tax registration entry is given without the actual tax identifier (registration number) inside it.

An invoice line is missing its VAT category code (Standard/Zero-rated/Exempt/Not subject).

The invoice has no invoice lines at all - at least one line item is required.

An invoice line is missing its line identifier (line number).

An invoice line is missing its invoiced quantity.

Each invoice line must state the unit of measure for the quantity billed (for example piece, kilogram, or hour).

An invoice line is missing its net amount.

An invoice line is missing the item's name/description.

An invoice line is missing the item's net unit price.

An item's net price is negative, which is not allowed.

An item's gross price is negative, which is not allowed.

If an invoice line gives both a start and an end date for its own period, the end date must be on or after the start date.

On a summary invoice, if an invoice line states its own billing period, the start and end dates must fall within the same calendar month.

For an invoice that is marked as both a full tax invoice and a summary invoice, each invoice line must show the start and end dates of its billing period.

An item's net price does not equal its gross price minus the price discount.

An invoice line is missing whether the item is a good or a service; this is required unless the invoice is a simplified tax invoice.

Within an item's unit price, you may record a discount but not a charge.

For an import-of-goods invoice, an item's country of origin is missing.

The base quantity used to calculate the unit price must be greater than zero.

A line item refers to more than one purchase order line number; it may only refer to one.

A line item's billing period appears more than once; it may only appear once per line.

A line item's price discount appears more than once; it may only appear once per line.

An item's net price does not match its gross price minus the price discount.

A line item's country-of-origin code is not a valid ISO 3166-1 country code.

A line item's billing period was given without a start date or an end date; at least one of the two must be filled in.

A note on a line item appears more than once; it may only appear once per line.

A line item's description appears more than once; it may only appear once per line.

The buyer's or seller's region code must be one of the standard Oman subdivision codes from the official list - a code outside this list is not valid.

The Seller's name is missing.

The Buyer's name is missing.

For an import-of-goods, import-of-services (reverse charge), profit-margin self-invoice, or special-zone-supply transaction, the seller identifier must include its scheme code, not just the identifier value.

The Seller's postal address is missing entirely.

The Seller's postal address is missing its country code.

The Buyer's postal address is missing entirely.

The Seller's postal address is incomplete - address line, city and postal code are all required fields for the seller.

The Buyer's postal address is missing its country code.

The Seller's contact telephone number is missing. Oman requires a reachable phone number for the seller on the invoice.

The Buyer's postal address is incomplete - address line, city and postal code are required for most invoice types.

For a self-billed invoice/credit note, import of services (reverse charge), profit-margin self-invoice, or import of goods, the buyer's country must be Oman.

The buyer's electronic address (used to route the invoice electronically) must be provided.

The seller's electronic address must be provided.

For a profit-margin self-invoice, the seller's country code must be Oman (OM).

The seller's name can be given only once.

The seller's trading name can be given only once.

The seller's legal registration number can be given only once.

The seller's additional legal information can be given only once.

The buyer's name can be given only once.

The buyer's legal registration number can be given only once.

The name of the party the goods were delivered to appears more than once; it may only appear once.

The buyer's trading name appears more than once; it may only appear once.

A self-billed invoice cannot also be marked as third-party, export, import of services, profit-margin, profit-margin self-invoice, or import of goods — but this invoice combines them.

A self-billed invoice and a third-party invoice are mutually exclusive classifications, but this invoice is marked as both.

For a special-zone-supply invoice where the seller's subdivision code is not 'MO', the seller must include an identifier using the Special Zone License Number scheme.

For a special-zone-supply invoice where the buyer's subdivision code is not 'MO', the buyer must include an identifier using the Special Zone License Number scheme, unless the buyer's electronic address is 997770000099.

For an import-of-goods invoice, the buyer must include an identifier using the Importer Customs ID scheme.

For an import-of-services (reverse charge) invoice, the seller's country code must not be Oman (OM).

When the buyer's electronic address is 997770000099, the invoice must include the Seller UUID, and it must be a valid version 5 UUID.

The Seller's or Buyer's electronic address scheme identifier is not one of the recognised Peppol (CEF EAS) codes - this identifies which network/registry the address belongs to.

The buyer's identifier (ID number) appears more than once; it may only appear once.

An extra address line for the seller's postal address appears more than once; it may only appear once.

An extra address line for the buyer's postal address appears more than once; it may only appear once.

An extra address line for the payee's postal address appears more than once; it may only appear once.

The invoice is missing its Oman 'transaction type' marker, or that marker is not a 20-character string of 1s and 0s with exactly one type switched on. This field tells the system what kind of invoice this is (full tax invoice, simplified invoice, export invoice, etc.) - every Oman PINT invoice must carry it.

The invoice is missing its issue TIME (not just the date). Oman PINT invoices need both an issue date and a time.

The invoice is marked as BOTH a Full Tax Invoice and a Simplified Invoice at once - it can only be one.

The invoice transaction type must mark it as either a full tax invoice or a simplified invoice - not both, and not neither.

Same check as above: the 'transaction type' field must be exactly 20 characters, made only of 1s and 0s.

The invoice has no invoice number. Every invoice needs a unique number.

The invoice is missing its unique ID (UUID), or the UUID is not a valid 'version 5' UUID. Oman requires every invoice to carry this system-generated identifier - it is normally produced automatically by invoicing software, not typed by hand.

The invoice has no issue date.

The invoice (or credit note) has no type code - the field that says whether this is a standard invoice, a credit note, a self-billed invoice, etc.

The invoice has no currency code.

The invoice does not state the final amount due for payment.

A credit note or debit note must include a reason code.

The 'transaction type' bitmap must have either its first position (Full Tax Invoice) or second position (Simplified Invoice) set to 1 - every invoice must be clearly one or the other.

The final amount due has more than 2 decimal places - money amounts should be rounded to 2 decimals.

A monetary amount is tagged with a currency other than the invoice's stated currency (outside the specific fields allowed to use the tax accounting currency instead).

A summary invoice cannot also be marked as continuous supply, export, profit-margin, profit-margin self-invoice, or import of goods — but this invoice combines them.

A continuous-supply invoice cannot also be marked as a summary invoice, deemed supply, profit-margin, profit-margin self-invoice, or import of goods — but this invoice combines them.

An export invoice cannot also be marked as self-billed, a summary invoice, deemed supply, import of services, profit-margin, profit-margin self-invoice, or import of goods — but this invoice combines them.

A deemed-supply invoice cannot also be marked as continuous supply, export, profit-margin, or profit-margin self-invoice — but this invoice combines them.

An import-of-services (reverse charge) invoice cannot also be marked as export, profit-margin, profit-margin self-invoice, import of goods, or self-billed — but this invoice combines them.

A profit-margin invoice cannot also be marked as a summary invoice, continuous supply, export, deemed supply, import of services, import of goods, or self-billed — but this invoice combines them.

A profit-margin self-invoice cannot also be marked as a summary invoice, continuous supply, export, deemed supply, import of services, profit-margin, import of goods, or self-billed — but this invoice combines them.

An import-of-goods invoice cannot also be marked as a summary invoice, continuous supply, export, import of services, profit-margin, profit-margin self-invoice, e-commerce supply, or self-billed — but this invoice combines them.

An e-commerce-supply invoice and a profit-margin self-invoice are mutually exclusive classifications, but this invoice is marked as both.

A simplified tax invoice cannot also be marked as self-billed, a summary invoice, export, import of services, profit-margin, profit-margin self-invoice, or import of goods — but this invoice combines them.

The invoice's issue date is in the future (checked against Oman/Muscat time). An invoice cannot be dated ahead of when it is actually issued.

The invoice uses the self-billed invoice or self-billed credit-note type code, but its transaction type is not marked as one of: self-billed, import of services, profit-margin self-invoice, or import of goods.

A currency code somewhere on the invoice is not a valid 3-letter ISO 4217 code (e.g. OMR, USD).

The invoice's own currency code is not a valid ISO 4217 code.

The tax accounting currency code is not a valid ISO 4217 code.

A general note on the invoice appears more than once; it may only appear once.