Sole proprietorship on a B2B contract

Moving from employment to a B2B contract in Poland means registering a JDG (jednoosobowa działalność gospodarcza, a sole proprietorship) and taking over duties your employer once handled. This article puts that month in order.

What changes when payroll disappears

Your employer acted as the withholding agent: the advance deducted, contributions paid, filings made. None of it disappears — only who does it changes.

• You create the document. The client will not invoice on your behalf: you describe the service, set the sale date and assign the number. From April 1, 2026 the sales invoice also travels to KSeF, the national e-invoicing system.
• The tax leaves your own account. Instead of a payslip deduction there is a tax advance, paid by the statutory monthly deadline to your individual tax micro-account (mikrorachunek podatkowy).
• Social security is a fixed amount, not a share of the invoice. Full social contributions to ZUS (Zakład Ubezpieczeń Społecznych) cost 1,788.29 zł a month, which is 21,459.48 zł a year; with voluntary sickness cover it is 1,926.76 zł a month. A new firm starts lower: ulga na start lifts the social ones for 6 months — the health contribution is still due — and the preferential basis then costs 456.18 zł. They fall due even when the client pays late.
• The deadlines are yours to track. Nobody reminds you about the advance or the annual return.

The three taxation forms people weigh up

You declare a form when registering and change it within the statutory window early in the year. Three realistically apply here.

• Ryczałt (flat-rate tax on recorded revenue) — charged on revenue itself, with no deduction for costs. Software-related services sit at 12%, the residual category at 8.5%, and the annual ceiling is 8,517,200 zł. The health contribution steps through brackets — 498.35 zł, 830.58 zł or 1,495.04 zł a month — not your invoice.
• Podatek liniowy (flat 19% tax) — one rate on income, so after costs. Health takes 4.9% of income and comes off income itself, up to 14,100 zł a year.
• Skala podatkowa (the progressive scale) — 12% up to 120,000 zł and 32% on the excess, with 30,000 zł tax-free. Health is 9% of income and reduces nothing.

Which one leaves more depends on the invoice and your costs — the B2B calculator puts the paths side by side, contributions included. The ryczałt rate is not a preference: it follows from the PKWiU classification of what you deliver, and the brackets are unpacked in the article on the health contribution.

One month on ryczałt, step by step

1. The invoice. You issue the document and send it to KSeF; the UPO, the official confirmation of receipt, comes back and stays with it. Automatic sending to KSeF is a switch you turn on yourself; it ships off.
2. The revenue ledger. Issued sales invoices stack up month by month under the rate in force then. A proforma or advance invoice (ZAL) creates no revenue yet; a correction lands back in the period it fixes.
3. The tax advance. The ledger yields the advance as a running total from January. One caveat: the app works it out from revenue alone — the statutory reductions for social security paid and 50% of the health contribution paid are not applied, so treat it as a starting point to verify.
4. The year. Two documents close it, both due by 30 April of the following year: the annual PIT-28 return and the JPK_EWP file with the whole ledger.

Where the app's role ends

In Biurko you keep the ledger and file the annual JPK_EWP, receiving the UPO. Outside it stay: settling your ZUS contributions, the annual PIT-28 or PIT-36L return, and the separate register of qualified rights from the IP Box article. VAT registers and the JPK_V7 exist only for an actively registered VAT payer (czynny podatnik VAT); whether you are one or VAT-exempt is decided separately from the taxation form and set out in the VAT rates and status article. A taxation form, a borderline classification or VAT status with a client abroad is worth checking with an accountant or tax adviser first.

When your client is abroad

An invoice in euros or dollars adds three settings rather than reshaping the month: one of eighteen currencies, the NBP table A rate for the day before the tax obligation arose — rolling back to the previous working day, or typed in by hand — and one of ten languages pinned to the contractor. Net and gross stay in the contract currency while VAT is additionally printed in złoty, and the "Reverse charge" note is yours to add. Conversion rules sit in the foreign currency article, the full contracting month on the B2B accounting page.