Start Preparing Your Annual Income Tax (IRS 2026) in Portugal from September 2025

The official deadline to file your Portuguese IRS for 2025 income is between April 1 and June 30, 2026. However, smart taxpayers know that waiting until spring creates stress, leads to missed deductions, and can even result in delayed refunds.

September 2025 is the time to start preparing for IRS 2026

1. Stay on Top of Deductions Early

By September, you’ll already have most of your 2025 expenses recorded. Medical, rent, education, insurance, and property receipts can all count towards your IRS deductions.

• These must be validated in the e-Fatura system by February 2026.

• Starting in September gives you plenty of time to review invoices and correct any errors.

2. Avoid the Busy Season in January and February

The beginning of the year comes with extra tax deadlines:

• January 31 – Model 44 submission for landlords without electronic receipts.

• February 15–17 – Household updates (marriages, divorces, dependents, etc.).

By organizing your IRS documents in September, you’ll enter the new year ready — instead of scrambling.

3. File Early, Get Refunds Faster

The IRS filing window is April 1 – June 30, 2026. Filing in early April often means:

• Refunds within two weeks (instead of waiting until July or August).

• Peace of mind, knowing your IRS is complete and accurate.

4. Plan Around Withholding and Tax Changes

The Portuguese government updates IRS withholding tables each year. These changes, effective from August and October, can affect whether you’ll receive a refund or have tax to pay.

• Reviewing payslips from September onward helps you predict your IRS outcome.

• You can adjust your financial planning before the official filing season.

5. Understand New Tax Benefits and Rules

Each year, the State Budget introduces IRS changes — from updated tax brackets to new deductions. For 2026, this may include:

• Adjusted income brackets to reflect inflation.

• Possible changes to Category B (self-employed) rules.

• Updated family-related benefits and deductions.

By starting in September, you’ll have time to understand how these changes impact your declaration.

Key IRS 2026 Deadlines (for 2025 income)

• January 31, 2026 → Model 44 (for landlords).

• February 15–17, 2026 → Household and invoice validation updates.

• March 16–31, 2026 → Deadline to correct expenses in e-Fatura.

• April 1 – June 30, 2026 → IRS filing period.

• July 31, 2026 → Expected settlement/refund notices.

• August 31, 2026 → Final deadline for payment or refunds.

Conclusion

Preparing for IRS 2026 doesn’t need to be stressful. By starting in September 2025, you can:

• Ensure all deductions are counted.

• Avoid the January–February rush.

• File early and get your refund faster.

• Stay ahead of tax changes.

👉 September is the smart month to begin — for a smoother, stress-free, and financially optimized IRS season in Portugal.