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Finnish reference number and RF reference: how to calculate them

Karma Accounts · Published 2 November 2026

A Finnish reference number (viitenumero) is a number of 4 to 20 digits that the seller puts on an invoice so that the payment can be matched to that invoice automatically. It is a base, such as the invoice number, followed by one check digit: multiply the base's digits from right to left by 7, 3, 1, 7, 3, 1 and so on, add up the products and subtract the sum from the next full ten. The RF reference (ISO 11649) is the international version: RF, two check digits calculated with the same mod 97 rule as an IBAN, and up to 21 letters or digits. It works on domestic and cross-border invoices. Both are worked through below.

Our reference number calculator does the sums for you; this article explains the method and when to use which reference.

What a reference number is for

The seller forms the reference, for example from the customer or invoice number, and prints it on the invoice. The payer types it in the reference field of the transfer, the bank checks it and passes it on, and the seller's accounting can match the payment to the open invoice by the reference instead of by reading a message. The check digit catches typing mistakes: if one digit is wrong, it no longer fits, and the payer's bank notices when the reference is typed in.

A reference number is not among the entries the VAT Act requires, so an invoice without one is still valid; the required entries are in our article on invoice requirements, and the whole job in how to invoice in Finland. Without a reference, though, payments may have to be matched by hand, and a bank barcode cannot be printed.

How to calculate a Finnish reference number

Finance Finland (Finanssiala), the finance industry's association, sets the rules:

• The base has 3 to 19 digits and the check digit is always added at the end, so a reference has 4 to 20 digits. Keep it short: a short reference is mistyped less often.
• Multiply the digits of the base from right to left by the repeating weights 7, 3, 1.
• Add up the products and subtract the sum from the next full ten. The difference is the check digit. If the difference is 10, the check digit is 0.
• Print the reference in groups of five digits counted from the right, with a space between them and without leading zeros.

Example 1: a reference from the invoice number 2026042

The next full ten is 90, and 90 − 88 = 2. The reference number is 20260422, printed 202 60422.

When the sum is already a full ten, the check digit is 0. From the customer number 1098: 8 × 7 = 56, 9 × 3 = 27, 0 × 1 = 0 and 1 × 7 = 7, which add up to 90. The reference is 10980.

For rent, maintenance charges, instalments and other recurring charges, Finance Finland advises leaving the instalment number out of the reference, because a payment is usually used for the oldest amount owed.

What an RF reference is and how it is built

The RF creditor reference follows the international standard ISO 11649:

• the letters RF
• two check digits, calculated with ISO/IEC 7064 MOD 97-10, the same rule as an IBAN's
• the creditor's own reference, up to 21 letters and digits, so at most 25 characters in all.

On paper it is printed from the left in groups of four characters. You may build it from your Finnish reference number, which keeps your matching simple, but under Finance Finland's current guidance it can also be formed freely within the ISO rules.

Example 2: the RF reference for 20260422

1. Add RF00 to the end of the reference: 20260422RF00.
2. Turn the letters into numbers, A = 10, B = 11 and so on, so R = 27 and F = 15: 20260422271500.
3. Divide by 97 and take the remainder. An ordinary calculator may not handle 14 digits exactly, so do it in pieces, as with an IBAN: 202604222 = 97 × 2 088 703 + 31. Put the remainder in front of the remaining digits: 3171500 = 97 × 32 695 + 85. The remainder is 85.
4. Subtract the remainder from 98: 98 − 85 = 13. A single-digit result gets a leading zero, such as 04.
5. Put RF and the two check digits in front of the original reference.

The RF reference is RF1320260422, printed RF13 2026 0422.

To check it, move RF13 to the end and convert the letters: 20260422271513. Divided by 97, the remainder must be 1. Here 202604222 again leaves 31, and 3171513 = 97 × 32 696 + 1, so the reference is valid.

Finnish reference or RF reference: which to use

Finnish banks accept and check both kinds wherever a payment is typed in. The Finnish reference is a national standard, and no decision has been made to phase it out. The RF reference is the one a foreign payer's bank can carry as a structured creditor reference in a SEPA payment, and Finance Finland's guidance names it as the reference for cross-border invoices. On domestic invoices it gives the seller no extra automation.

If your RF references are built from Finnish references, your bank's Finnish-format payment reports drop the first four characters, RF and the check digits, and what is left is exactly your Finnish reference, so your matching keeps working.

The reference on the invoice and in the barcode

Print the reference in the payment details, in the field marked Viitenumero, and repeat it in the invoice details. The other words on a Finnish invoice are in our Finnish invoice terms in English.

The bank barcode (pankkiviivakoodi) holds the payment details as 54 digits. Finance Finland's bank bar code guide has two versions:

The bank barcode may be printed only for an IBAN starting with FI, and only with a reference. If an RF reference has letters after RF, they cannot go into the barcode: either no barcode is printed, or a version 5 barcode is printed with zeros in its reference field. The reference itself is still printed on the invoice. The invoice can always be paid by typing the details in.

The virtual barcode (virtuaaliviivakoodi) is the same 54 digits printed as text, which the payer can paste into an online bank that accepts it. For 1 240.00 euros to the test account in Finance Finland's guide, FI79 4405 2020 0360 82, due 15.12.2026:

• version 4, reference 202 60422: 479440520200360820012400000000000000000020260422261215
• version 5, reference RF13 2026 0422: 579440520200360820012400013000000000000020260422261215

Our free invoice template builds the reference from the invoice number and prints both barcodes for you.

Why the payer must use the reference, not a message

Finance Finland's credit transfer guide treats the reference and the message as alternatives: if both are given, only the reference is passed on. A message in place of the reference still brings the money, but the payment cannot be matched by the reference, someone may have to sort it out by hand, and the customer may get a needless payment reminder.

The payer must also copy the reference exactly as printed and must not turn a Finnish reference into an RF reference or the other way round: the seller matches by the reference that was on the invoice.

Tax payments: the Tax Administration's own reference numbers

Taxes are paid with references the Tax Administration gives you; you never calculate them yourself.

• Companies, partnerships and other entities, such as limited companies, general and limited partnerships, associations and foundations, pay with the general reference number for taxes, unique to each taxpayer, or with the tax-specific references. Use one way only: mixing them can allocate payments to other taxes than you meant. The general reference is shown in MyTax (OmaVero) and on the Tax Administration's decisions; the tax-specific references only in MyTax or through its interface.
• The general reference cannot be used for taxes under a payment arrangement or in enforcement, OSS VAT, inheritance tax or one-off excise duty guarantees. Transfer tax is best paid with its own reference: paid with the general reference, it is settled only on its due date, after any taxes that fall due earlier.
• Sole traders and private persons pay with tax-type references. A private person finds them in MyTax or on the tax decision.

The Tax Administration's account numbers are in MyTax too. It does not publish them on vero.fi and warns about scam messages in its name, so take payment details from MyTax, not from an email.

Common mistakes

• The reference in the message field. The money arrives but cannot be matched by the reference.
• A guessed check digit. A wrong check digit fails the check at the payer's bank, so calculate it rather than guess.
• Wrong grouping. Finnish references go in groups of five from the right without leading zeros, RF references in groups of four from the left.
• Instalment numbers in references for recurring charges.
• Letters after RF in an RF reference when you want a bank barcode.
• Long references, which are mistyped more often.

Frequently asked questions

How do I calculate a Finnish reference number?

Multiply the base's digits from right to left by 7, 3, 1, 7, 3, 1, add up the products and subtract the sum from the next full ten. The result is the check digit, or 0 if the result is 10. Put it after the base.

What is an RF reference number?

The international creditor reference under ISO 11649: RF, two check digits worked out with mod 97 and up to 21 letters or digits. To make one from a Finnish reference, add RF00 to its end, turn R and F into 27 and 15, take the remainder on division by 97 and subtract it from 98, adding a leading zero to a single digit. RF and these two digits go in front of the Finnish reference.

Which reference should I use for a customer abroad?

The RF reference. It is the international standard, and a SEPA transfer carries it as a structured reference. Finnish banks accept it on domestic invoices too.

What we do

We keep the books for sole traders and limited companies, match sales invoices to payments and set up invoicing so that the references work. See sole trader accounting and limited company accounting, or request a quote.

Sources

• Finance Finland: forming a Finnish reference number (PDF)
• Finance Finland: structure of the RF creditor reference, ISO 11649 (PDF)
• Finance Finland: calculating the RF reference check digits (PDF, in Finnish)
• Finance Finland: introducing the RF reference in a Finnish company (PDF, in Finnish)
• Finance Finland: bank bar code guide, version 5.3 (PDF)
• Finance Finland: credit transfer form guide (PDF, in Finnish)
• ISO 11649:2009, structured creditor reference to remittance information
• Tax Administration: VAT invoice requirements, detailed guidance
• Tax Administration: bank account numbers and reference numbers for businesses
• Tax Administration: account and reference numbers for individuals (in Finnish)
• Tax Administration: how payments are used for different taxes (in Finnish)

Please note: this is general information about Finnish rules, not advice for your own situation, and the rules change. Ask us before you act on it.

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