Filing a PIT return as an entrepreneur involves more than just choosing the right form. Find out which form to use, which deadlines to watch and which mistakes to avoid in 2026.
Every entrepreneur — regardless of legal form or scale of business — is required to file an annual income tax return. Although submitting a PIT declaration may seem like a formality, in practice it involves many decisions that affect the amount of tax liability. The choice of form, the method of recording costs, the deadlines for advance payments and the annual return — these are all areas where a minor mistake can result in additional tax due, interest charges or even a tax audit. In this article we explain step by step how to correctly file a PIT return as an entrepreneur: which forms apply to which taxation method, what the deadlines are and what to avoid at all costs.
The choice of the correct form depends primarily on the selected method of taxation. Entrepreneurs report their business activity using three main declarations: • PIT-36 — for entrepreneurs keeping a tax revenue and expense ledger (KPiR) or full accounting books who have chosen taxation on a progressive tax scale (12% and 32%). This form covers income from various sources and allows the use of a wide range of tax reliefs. • PIT-36L — for entrepreneurs taxed under the flat-rate income tax at 19%. A straightforward structure, but without the possibility of using most tax reliefs or filing a joint return with a spouse. • PIT-28 — for taxpayers subject to lump-sum tax on recorded revenue (ryczałt od przychodów ewidencjonowanych). The tax base here is revenue, not income, so costs of obtaining revenue are not deducted. Entrepreneurs who are partners in partnerships (e.g. jawna, komandytowa) also report their share of profits through the relevant PIT form, in proportion to their ownership interest.
Knowing the deadlines is essential to avoiding penalties. The following key dates apply in 2026: • 30 April 2026 — deadline for submitting PIT-36 and PIT-36L for the 2025 tax year. This is also the date by which any outstanding tax must be settled. • 30 April 2026 — deadline for PIT-28 (ryczałt). Note: until recently, taxpayers on the lump-sum method submitted their return by the end of February; however, this deadline has been unified with the other forms for several years now. Entrepreneurs required to make monthly or quarterly advance income tax payments should bear in mind that the annual return is the final settlement — any overpayment can be refunded, while any shortfall must be paid. Declarations are submitted exclusively electronically — via the e-Urząd Skarbowy system or directly from accounting software compliant with KSeF and JPK requirements.
The annual PIT return is only a summary. Throughout the year, an entrepreneur is required to make regular advance income tax payments. Under progressive scale or flat-rate PIT taxation, advance payments are made monthly (by the 20th day of the following month) or quarterly — provided the conditions for the so-called small taxpayer status are met. Under the lump-sum method (ryczałt ewidencjonowany), the deadlines are analogous: monthly or quarterly advance payments. An important rule: failure to make an advance payment on time results in interest charges for late payment, and significant arrears may lead to the initiation of tax proceedings. In 2026, with mandatory KSeF and the more detailed JPK_PKPIR structures, tax authorities have significantly broader real-time access to data — meaning discrepancies are detected much faster.
The health insurance contribution (składka zdrowotna) is one of the factors that has most strongly affected the combined tax and social security burden on entrepreneurs in recent years. In 2026, the rules depend on the method of taxation: • Progressive scale and flat-rate income tax: the health contribution amounts to 9% or 4.9% of income (for the scale and flat rate respectively), with a specified monthly minimum. • Lump-sum tax (ryczałt ewidencjonowany): the contribution depends on the level of revenue and is set at three revenue thresholds. Entrepreneurs on the flat-rate income tax may deduct part of the health contribution from their income (up to the statutory limit), which partially mitigates its impact on the PIT liability. Under the progressive scale, the health contribution is not deductible from tax or income. A precise calculation of the total burden should form part of the analysis when choosing or changing the method of taxation.
The experience of Danexis accounting office shows that entrepreneurs repeatedly make the following mistakes: 1. Choosing the wrong form — for example, submitting PIT-36L despite operating under the lump-sum (ryczałt) method. 2. Incorrectly classifying expenditure as tax-deductible costs — not every business purchase qualifies as a tax cost. Mixed-use expenses (private and business) are particularly risky. 3. Failing to adjust advance payments — when income changes during the year, the amount of advance payments must be adjusted accordingly; otherwise, arrears accumulate. 4. Lack of documentation for claimed reliefs — an entrepreneur must hold proof of the expenditure incurred (e.g. for the R&D relief or the purchase of a cash register). 5. Errors in related declarations — PIT-36 or PIT-36L are often submitted together with attachments (e.g. PIT/B for business activity), and omitting these results in a notice from the US (Urząd Skarbowy). 6. Missing the deadline without submitting an extension request — even a one-day delay may result in a fine if a voluntary disclosure (czynny żal) has not been filed.
A sound PIT settlement begins well before 30 April. Here is a practical checklist: • Closing the accounting year — verifying all entries in the KPiR, lump-sum revenue register or accounting books. • Verifying costs — checking that all recorded expenses have a legal basis and supporting documentation (invoice, contract, proof of payment). • Analysing available reliefs — the R&D relief, IP Box relief, robotisation relief, and the relief for entrepreneurs investing in PSI/SSE zones. • Reconciling advance payments — comparing advance payments made against the total tax due for the full year. • Verifying declaration data — NIP, registered address, legal form — particularly important following any changes in official registers. In 2026, with mandatory KSeF and the expanded JPK structure, tax authorities have access to an ever-growing volume of comparative data. Complete and consistent documentation is not only a legal obligation but also real protection against disputes.
Filing a PIT return as an entrepreneur is a process that requires careful attention at every stage — from choosing the correct form, through timely advance payments, to the accurate treatment of health contributions and tax reliefs. Mistakes in this area can cost significantly more than working with an experienced accounting office. If you want to be confident that your return is filed correctly and optimally from a tax perspective, contact the Danexis team — call +48 780 760 666, write to kontakt@danexis.pl or visit us at ul. Braniborska 74/20 in Wrocław.