Invoice numbering in Lithuania: series, number and the rules

A Lithuanian invoice must carry a series and a number.

You choose the series yourself, from letters or digits; the number must be formed in ascending sequence; and the same number may not appear on two invoices within the same series.

This is set out in the rules approved by Government Resolution No. 780: rule 6 applies to the ordinary invoice (sąskaita faktūra) and rule 12 to the VAT invoice (PVM sąskaita faktūra).

The legal texts we read prescribe no format: no number of digits, no hyphen between series and number, no year in the series.

For the VAT invoice the VAT law adds that the series and number must allow the invoice to be identified.

This is an invented example: the names and codes are not real.

Vardenis Pavardenis is self-employed under a Lithuanian individual activity certificate (individuali veikla), is not a VAT payer and uses a single series, "SF". In September he issues three invoices.

Each names the seller as Vardenis Pavardenis, individual activity certificate No. 000000.

The first invoice:

• Invoice, series SF, No. 014
• Date of issue: 2026-09-03
• Buyer: UAB „Pavyzdys“, code 000000001
• Service: text editing, 10 hours at EUR 30.00
• Total: EUR 300.00

The next two differ only in these lines:

• Series SF, No. 015, issued 2026-09-12 to MB „Pavyzdinė dirbtuvė“, code 000000002: 4 hours at EUR 30.00, total EUR 120.00
• Series SF, No. 016, issued 2026-09-26 to UAB „Pavyzdys“, code 000000001: 6 hours at EUR 30.00, total EUR 180.00

The number does not depend on the buyer: two buyers, one sequence. There is no VAT because the seller is not a VAT payer, so the total is quantity multiplied by price.

You can prepare such an invoice with our free invoice tool: you type in the series and number, and the tool shows whether any required information is missing.

Rule 6 of the Rules for issuing and recognising accounting documents used to calculate taxes says that an invoice must have a series and a number, and gives three requirements:

1. 01The number must be formed in ascending sequence (rule 6.1).
2. 02The number must be based on one or more series which, at the choice of the business, may be composed of letters or of digits (rule 6.2).
3. 03The business must ensure the number is unique: different invoices may not show the same number based on the same series (rule 6.3).

Rule 12 repeats these requirements for the VAT invoice.

In addition, Article 80(1)(2) of the Law on Value Added Tax lists among the required information "the series and number of the VAT invoice which allow the VAT invoice to be identified".

Why this matters to your buyer: point 2.1 of Resolution No. 780 states that an invoice and a VAT invoice have no legal force, that expenses may not be recognised as costs on their basis, and that input VAT may not be deducted, if they lack any of the required information set by the legal acts, except in the cases the rules provide for.

The series and number are part of that information.

The full list is in our guide to invoice requirements in Lithuania; VAT payers should see the required information on a VAT invoice.

Three schemes that fit the wording of the rules:

• One series for good. Series "SF" with numbers 001, 002, 003 and so on, whatever the year.
• A separate series for each year. Series "2026" with numbers from 001, then series "2027" from 001 again. The number repeats but the series differs, and rule 6.3 forbids only the same number based on the same series.
• A separate series for each line of work. Series "KP" for consulting and "MK" for training, each with its own ascending sequence.

The rules say "of letters or of digits" and do not speak separately about a series that mixes the two, such as "SF26".

We cannot say from the text alone whether such a series is acceptable, so check with an accountant before choosing one. Our examples use letters only or digits only.

Every series is another sequence to look after, so one series leaves fewer chances for a mistake.

The rules say "in ascending sequence" (didėjančia seka). The words "without gaps" or "consecutive" do not appear in the texts we read, and those texts do not say directly that a later number must carry a later date.

That does not mean gaps are allowed: the text is silent, and this guide does not assess how the tax administrator reads it.

We suggest numbering one after another, in the order the invoices are issued, so that you never have to explain why 017 follows 015. This is practical advice, not a quotation from a legal act.

A repeated number within the same series directly contradicts rule 6.3 (rule 12.3 for the VAT invoice). These rules contain no procedure for correcting such a mistake.

Article 7(5) of the Law on Financial Accounting sets a general rule: accounting documents that support transactions carried out in money may not be corrected; if a mistake is made, a new accounting document is prepared, and the document with the mistake is treated as invalid and kept together with the other accounting documents of the reporting period.

Whether and how this applies to an invoice already sent to the buyer is a question for an accountant.

Paper documents have their own rule.

Under rule 31, a paper document spoiled while being issued is marked at once with the word „Anuliuota“ (cancelled) and the date of cancellation, and the person who issued it confirms the cancellation with a signature.

It is kept for the retention periods set by the Chief Archivist of Lithuania.

A skipped number. The texts we read do not describe what to do after skipping a number.

Do not renumber invoices you have already issued, note in your list which number was not used and why, and speak to an accountant.

A different case is a change in the taxable value or quantity, a discount or a return of goods after the invoice is issued.

Article 83(1) of the Law on Value Added Tax provides that such changes are documented by a credit document issued by the person who issued the original document or, if the parties agree, by a debit document issued by the buyer, provided the buyer is a VAT payer.

See the guide to credit and debit invoices.

Under paragraph 3 of that article, such a document states the date of issue, series and number of the VAT invoice being adjusted, where it is possible to establish exactly which document that is.

The texts we read do not tie numbering to the calendar year and do not require starting from the first number in a new year.

A continued sequence meets the rules, because the numbers keep ascending and do not repeat: SF No. 047 in December, SF No. 048 in January.

To start the year from 001, choose a new series. Restarting the same series would put two identical numbers in it, which rules 6.3 and 12.3 forbid.

This is our conclusion from the wording of those rules; they have no separate provision about the start of a year.

Rule 7 obliges businesses to keep records of the invoices they receive and issue.

Article 78(5) of the Law on Value Added Tax obliges taxable persons to keep registers of the VAT invoices they receive and issue; the requirements for those registers are set by the central tax administrator.

We do not examine those requirements here, so confirm the form and deadlines for your case with an accountant.

A few habits keep the sequence in order. They are practical suggestions, not legal requirements:

1. 01Keep one list (a notebook or a spreadsheet) with one row per invoice: series, number, date, buyer, amount.
2. 02Before issuing an invoice, look at the last row and add the new one, and only then fill in the document.
3. 03Write the number with leading zeros, 001 rather than 1, so that files sort in the right order.
4. 04Name the file after the series and number, for example "SF-016". Two files with the same name show a repeat at once.
5. 05If several people issue invoices, each can have a separate series so that the numbers do not collide.

The guide to the self-employed invoice has an example with all the required information.

The invoice tool is free, needs no registration and keeps the draft in your browser.

It covers the ordinary invoice and the VAT invoice with rates of 21, 12, 5 and 0 per cent, shows which required information is missing, and prints or saves a PDF through the browser's print window.

It is not accounting software. It keeps no register, sends nothing to the State Tax Inspectorate and does not increase the number for you, so you enter the series and next number from your own list.

It does not cover reverse charge, margin schemes, or credit and debit documents.

This guide explains what the legal texts say and is not tax advice. If your numbering already contains a mistake, or you are changing the scheme mid-year, decide with an accountant.