What is left from an invoice as a sole trader

The gross amount lands in your account, but the VAT was never yours, the income tax advance has to be set aside, and Polish social contributions are owed whether or not anything came in this month. Below is what actually remains.

Flat rate 12%, VAT registered, full contributions

6 000,00 zł net a month

10 000,00 zł net a month

20 000,00 zł net a month

Computed with 2026 rules, assuming the same monthly invoicing all year: the health contribution bracket depends on annual revenue.

What the contributions are

A ZUS statement has three separate lines: social contributions (pension, disability, sickness, accident), the Labour Fund and the health contribution. The sickness one is voluntary.

Common questions

What is left from a 10,000 zł net invoice on the flat rate?

12,300 zł lands in the account. The VAT (2,300 zł) was never yours, the tax advance is about 919 zł and full contributions are 2,757.34 zł, leaving roughly 6,323 zł — assuming the same invoicing all year and no costs.

Why does a larger invoice leave proportionally less?

The health contribution on the Polish flat rate has three brackets set by annual revenue: up to 60k, up to 300k and above. Crossing a threshold raises it in a step, not gradually.

Are contributions owed in a month with no income?

Yes. They are owed for a month of trading, not per invoice, which is why they are counted once a month here — three invoices in March do not mean three bills.

Does the calculator account for costs?

No, deliberately. Costs are individual, and guessed costs would overstate what is left. The app takes your real ones.

Is this tax advice?

No. It is a calculation from published rates, useful for planning. Check it with an accountant before paying.