Tax Changes Calendar 2026
What, When, and Who Is Affected
2026 brings groundbreaking tax system changes. KSeF becomes mandatory for everyone, VAT regulations change, CIT, PIT, ZUS rules shift, and new employee protections emerge. This practical calendar covers all key dates, deadlines, and changes you must know. Whether you're self-employed or running a corporation — this guide prevents surprises.
Introduction — Why 2026 Is a Pivotal Tax Year
For years, Poland has been adapting European and international tax standards. 2026 is special — all planned reforms take effect simultaneously. Both individual entrepreneurs and large corporations must adapt systems and processes. The biggest change is mandatory e-invoicing via KSeF (National e-Invoicing System). But that's not all — minimum wage, ZUS rates, VAT limits, tax brackets, and numerous other rules change.
January 2026 — New ZUS Rates, Minimum Wage, and Tax Limits
New Minimum Wage
From January 1, 2026, minimum wage becomes 4,500 PLN gross (estimated; exact amount announced by Ministry of Labor). This increases employer costs for all minimum-wage workers. Update employment contracts and payroll calculations immediately.
New ZUS Contribution Rates
From 2026, ZUS rates change:
- Retirement (Old-age): 19.52% of wage base
- Disability: 8% (unchanged)
- Accident: ~1.4% (average, varies by industry)
- Health (NFZ): 9% (unchanged)
Small ZUS Plus Limits Change
The Small ZUS Plus relief changes conditions. From 2026, revenue threshold increases to 120,000 PLN annually (previously lower). More entrepreneurs qualify for preferential rates.
Cash Basis PIT (PIT-K) Available
From January 2026, taxpayers can file PIT on cash basis (PIT-K) instead of accrual. Income and expenses are recognized when received/paid, not when invoiced. Conditions: revenue under 200,000 PLN, no employees (with exceptions), business operation 3+ years.
February 2026 — KSeF Mandatory for Large Firms (200M+ PLN Revenue)
From February 1, 2026, all firms with revenue exceeding 200 million PLN annually must use KSeF (National e-Invoicing System).
What Is KSeF and How Does It Work?
KSeF is a central e-invoicing system run by the Ministry of Finance. Instead of traditional invoicing, all invoices must be submitted directly to KSeF. The system verifies accuracy and forwards to recipients automatically. Benefits: VAT fraud reduction, centralized data, automatic verification.
March-April 2026 — Full KSeF Mandate and SLIM VAT 4
April 1, 2026: KSeF becomes mandatory for all VAT taxpayers (B2B transactions). July 1, 2026: Extended to B2C transactions. October 1, 2026: Complete mandate for all subjects.
SLIM VAT 4 Simplifications (April 2026)
From April 2026, VAT simplifications ("SLIM VAT 4") take effect:
- Changed VAT settlement rules for small firms
- Simplified reporting requirements
- Modified exemption thresholds
- New relief mechanisms for micro-businesses
These changes aim to reduce compliance burden for small enterprises while maintaining control.
April-May 2026 — PIT Filing, E-Delivery Mandate
April 20, 2026: Deadline for PIT filing for 2025 tax year. File PIT-36, PIT-37, PIT-38 (depending on income source). Same deadline applies for CIT-8 (corporate tax) and VAT declarations.
E-Delivery Becomes Mandatory (May 2026)
From May 2026, all business entities must accept official documents via e-delivery system. This becomes mandatory method for receiving tax office correspondence, court notices, and official communications.
June-September 2026 — Corporate Tax Changes and Higher Exemption Limits
CIT Rate Adjustments (June 2026)
From June 2026, corporate tax (CIT) undergoes reforms affecting larger corporations. Rate remains 19% for most firms, but relief mechanisms and tax credit rules change.
Increased Revenue Thresholds for Various Tax Forms (September 2026)
Several revenue-based thresholds increase in September 2026, allowing more firms to use simplified reporting.
October 2026 — Small Business Relief Program and Flat Rate Changes
Increased Flat Rate Limits (October 2026)
From October 2026, revenue limits for flat-rate taxation (ryczałt od przychodów ewidencjonowanych) increase, enabling more self-employed to benefit. Exact thresholds announced by Ministry of Finance.
Small Business Exemptions Expanded
Relief programs for micro-businesses expand, reducing compliance burden for firms under 250 thousand PLN annual revenue.
Ongoing Changes: Global Minimum Tax 15% and Tax Fraud Prevention
Global Minimum Tax (Pillar 2) Implementation
Poland gradually implements OECD's Global Minimum Tax 15% to prevent aggressive tax planning. Primarily affects corporations with revenue exceeding 750 million EUR globally. Large corporations must ensure effective tax rate meets 15% threshold. Polish authorities introduce specific rules for multinational enterprise reporting.
Enhanced Tax Fraud Detection
Tax authorities strengthen monitoring of VAT fraud, transfer pricing, and profit shifting. Firms should ensure:
- VAT documentation is proper and thorough
- Related-party transactions have justified pricing
- Cross-border transactions properly reported
- Financial records complete and auditable
2026 Tax Deadlines Quick Reference
| Date | What | Who | Where |
|---|---|---|---|
| Jan 20 | PIT-11 settlements (from 2025) | Employers | Tax Office |
| Feb 1 | KSeF mandatory (200M+ revenue) | Large firms | KSeF system |
| Apr 1 | KSeF mandatory (B2B) | All VAT taxpayers | KSeF system |
| Apr 20 | PIT, CIT, VAT for 2025 | All taxpayers | Tax Office |
| May 1 | E-delivery mandatory | All entities | E-delivery system |
| Jul 1 | KSeF mandatory (B2C) | All VAT subjects | KSeF system |
| Oct 1 | KSeF fully mandatory | All entities with VAT | KSeF system |
How to Prepare for 2026 Tax Changes
1. Audit Your Current Systems
Check if your accounting software supports KSeF, e-delivery, and new JPK formats. If not, upgrade or switch providers.
2. Train Your Team
New systems require understanding. Invest in employee training on KSeF, e-delivery, and updated tax rules.
3. Update Documentation
Review employment contracts, supplier agreements, and internal procedures. Ensure compliance with new regulations.
4. Consult a Tax Advisor
Complex changes benefit from professional advice. A tax advisor helps optimize strategy and ensure compliance.
5. Create Implementation Timeline
Plan software updates, staff training, and process changes months before deadlines. Don't wait until March/April.
FAQ: Most Asked Questions About 2026
Q: If my revenue is under 200M PLN, when must I start KSeF?
A: From April 1, 2026, for B2B invoices. From July 1, 2026, for B2C invoices. From October 1, 2026, it's fully mandatory.
Q: Can I continue paper invoicing after April 2026?
A: For domestic B2B transactions — no. From April 2026, e-invoicing via KSeF is mandatory.
Q: What if my software doesn't support KSeF?
A: You must switch to compliant software. It's mandatory, not optional. Most major programs have KSeF modules by 2026.
Q: Are there penalties for late KSeF filing?
A: Yes. 100 PLN per invoice per day of delay (up to 30,000 PLN per month). Compliance is essential.
Q: Do freelancers need KSeF?
A: Only if registered as VAT taxpayer. Non-VAT self-employed don't need KSeF, but may be required from October 2026 for all invoices.
Piotr Nowak
Position: Tax Advisor, Accounting365
Credentials: Master's degree from SGH (Warsaw School of Economics), 18 years tax consulting experience
Piotr specializes in corporate and personal income taxation, VAT optimization, and international tax planning. He advises firms on compliance with new regulations and tax-efficient strategies.