How to organise invoices and receipts for a Polish business: a 10-minute weekly system

Catch each document where it arrives, save it into one folder per month under a name that says what it is, and once a week compare that folder with your bank account. That is the whole system.

It works for a JDG (jednoosobowa działalność gospodarcza, a sole trader business) and for a small sp. z o.o. (a limited company), with or without an accountant.

Where your documents come from

Most lost invoices are not lost. They are sitting in a place you forgot to look. A Polish business in 2026 gets its paperwork from five places:

KSeF (Krajowy System e-Faktur) is the national e-invoicing system. Every business has received invoices through it since 1 February 2026, and almost every business has had to issue its invoices to other businesses there since 1 April 2026 at the latest. There are three things it does not do:

• It sends no notifications. An invoice counts as received when KSeF gives it a number, whether or not anyone looks.
• It rarely holds foreign invoices. Foreign suppliers are not obliged to use it, so their invoices keep arriving by email or in portals. See the invoices KSeF won’t collect.
• It misses some Polish invoices until the end of 2026. A seller that has never gone over 10,000 PLN gross of business invoices in a month may still send a PDF or paper invoice until 31 December 2026. Shops may also still give you an invoice from the till outside KSeF until then.

Tip: since 1 February 2026 a business buyer must give its NIP to the seller. An invoice without your NIP does not reach your KSeF account, so put your NIP in every online account that bills you.

A folder structure that works

KSeF stores the invoices that pass through it. Every other invoice you issue or receive (PDFs, paper, foreign invoices, receipts with your NIP) is yours to keep. The VAT Act asks you to keep these divided by settlement period (the month or quarter you report VAT for), easy to find, legible and authentic, until the tax can no longer be collected.

A month is the natural period, so build around it:

Business/
  2026/
    09-September/
      Sales/
      Costs/
      Statements/
    10-October/
      ...
    Contracts/
    Letters/

• Sales: every invoice you issued, including any issued outside KSeF.
• Costs: every invoice and receipt for what you bought, Polish and foreign.
• Statements: the month’s statement for each business account.
• Side folders at the year level hold what is not monthly: contracts, letters from ZUS or the tax office, the car’s papers.

File a document in the month it belongs to. If an invoice dated 30 September arrives on 3 October, it still goes into September, because that is where your accountant will look for it.

Keep the folder somewhere backed up (iCloud Drive, Google Drive, Dropbox or a disk you copy). You will need it for years, and the tax office can ask for immediate access to the invoices you keep. Our guide to folders and file names goes into more detail.

File names you can read in a year

Suppliers name files invoice.pdf, INV-000123.pdf or a string of numbers. Ten of those in one folder tell you nothing. Rename each file as you save it:

The date first makes the folder sort itself. The seller and the amount let you find a document from the bank line alone.

Keep foreign amounts in their own currency. For income tax, the conversion to złoty uses the average rate of NBP (the Polish central bank) from the last business day before the cost, and your accountant or your software does it.

For foreigners: invoices in English are normally kept in their original language. The tax office can ask for a Polish translation, at your cost, during proceedings or an audit. Translate only when you are asked.

Paper receipts: photograph them and keep the original

A plain till receipt names the shop but not you, so on its own it may not be enough to prove a business cost. Two habits fix most of that:

1. Give your NIP before the receipt is printed. Until 31 December 2026, a receipt showing your NIP for up to 450 PLN gross (or 100 EUR) counts as a simplified invoice. If the receipt has no NIP, the shop may not issue you a business invoice later.
2. Photograph it the same day and save the photo in the month’s Costs folder with a proper name. Thermal paper fades, and the law asks that documents stay legible.

Then put the paper in an envelope for that month. The law does not plainly say that a photo of a paper receipt can replace the original, so keep both and ask your accountant before you throw anything away.

From 1 January 2027 a receipt with your NIP no longer counts as an invoice. If you need an invoice, ask for one, and the shop issues it in KSeF to your NIP. Our guide to receipts and invoices explains the rules.

The 10-minute weekly routine

Pick a day, for example Friday, and do the same five things:

1. Inbox: move every invoice email into the month’s Costs or Sales folder, renamed.
2. Portals: download anything new from the foreign accounts that bill you.
3. KSeF: open the invoice list, or check that your software pulled the week’s invoices.
4. Wallet: photograph the week’s receipts and put the paper in the envelope.
5. Bank: scroll through the week’s payments and tick each one against a document.

On the first working day of the month, add one step: download the previous month’s statement for every business account. That includes foreign-currency accounts and services such as Revolut, Wise, PayPal or Stripe.

Accounting contracts usually ask for the month’s documents by the 5th–10th. A month you kept up week by week is ready to send on the 1st. The full list is in what to send your accountant.

Check the bank before your accountant asks

The bank statement is the only complete record of the month. Every business payment on it needs a document behind it, and every cost document should have its payment. When a line has nothing, you find out now, not when the accountant writes on the 12th.

Card payments abroad are the lines most often left without a document. Our guide to matching payments to invoices walks through the check line by line.

How long you keep it

Tax documents are kept until the tax liability expires: 5 years from the end of the year in which the tax was due. For a sole trader:

A company keeping full accounts must also keep its books and most documents for at least 5 years from the start of the year after the financial year. The tax rule above usually ends later, so follow the longer of the two.

Keep a document longer while it still affects a later year’s tax, for example the invoice for equipment you are still depreciating. Ask your accountant before you throw such papers away.

Invoices in KSeF are stored there for 10 years from the end of the year they were issued. Receipts, foreign invoices and statements are only in your folders, which is one more reason to keep everything together, by month.

Plain folders, an accounting app, or a filing app?

Komplet reads each invoice or receipt on your Mac (text, or on-device OCR for photos), files it into your year and month folders under a readable name, and pairs it with the payment on your bank statement so the gaps show. At the end of the month, its “Prepare for my accountant” button builds one folder and a ZIP with every document, the statements, and a summary your accountant can read.

What to do next

1. Create this year’s folder with twelve month folders, each with Sales, Costs and Statements.
2. List every foreign supplier that bills you and where its invoices are downloaded.
3. Add your NIP to every online account, and give it at every till.
4. Put a 10-minute appointment in your calendar for every Friday.
5. At the start of each month, download the statements and send the month in one go.