ON Time | Tax Calendar - August 2026

August is one of those months when no two businesses experience exactly the same reality. While some take the opportunity to slow down, others enter one of the busiest periods of the year. Whatever your situation, one thing remains the same: important deadlines are still part of the calendar.

When routines change, it's only natural that the way you manage your day-to-day operations changes too. Some tasks get pushed back to the following week, responses take longer than usual and certain matters are temporarily put on hold. That's exactly when having a clear overview of the month becomes even more valuable.

To make things easier, we've brought together the key dates for August in one simple and practical place. This way, you can keep track of the most important deadlines without wasting time searching for information or missing what really deserves your attention.

Throughout August, simply come back to this calendar whenever you need it. A quick check may be all it takes to keep your month on track.

Throughout the month

• IRS / IRC: Submit Model 30 Declaration electronically by entities paying income to taxpayers who are non-residents in Portugal, relating to income paid during the month of July.
• VAT: Submit electronically requests for VAT refunds relating to VAT incurred during the current calendar year in another EU Member State, as well as VAT incurred in Portugal by taxable persons established in third countries, whenever the refundable amount exceeds €400 and relates to a period of at least three consecutive months, in accordance with Decree-Law No. 186/2009 of 12 August.

By 31 August

• IRS: Submit the Monthly Salary Declaration (Declaração Mensal de Remunerações) electronically by entities paying employment income subject to IRS, including income that is exempt or excluded from taxation under Articles 2, 2-A and 12 of the Portuguese Personal Income Tax Code. This declaration reports employment income, tax withholdings, mandatory social security contributions, legal healthcare contributions and trade union membership fees relating to the previous month.
• IRS / IMT / Stamp Duty: Submit Model 11 Declaration electronically by notaries, other public officials performing notarial duties, and professionals or entities authorised to certify private documents covering acts or agreements subject to income or property taxation, reporting all notarial acts carried out during the previous month.
• VAT: Complete the classification of invoices relating to the corresponding transactions on the Portuguese Tax Portal and confirm the provisional VAT return made available directly through the portal by the Portuguese Tax and Customs Authority (AT). This obligation applies to retailers subject to the special VAT scheme established under Article 60 of the Portuguese VAT Code (CIVA) and relates to the second quarter.
• VAT: Submit the Recapitulative Statement electronically by monthly VAT taxpayers who carried out intra-Community supplies of goods and/or services during the previous month to taxable persons registered in other EU Member States, where those transactions are taxable in the destination country under Article 6 of the Portuguese VAT Code. This also applies to quarterly VAT taxpayers whenever the total value of intra-Community supplies to be reported exceeds €50,000 during the current quarter (or in any month within that quarter).
• IRS / IRC / VAT: Communicate electronically the details of invoices issued during the previous month, or report the absence of invoices, by individuals and legal entities with their registered office, permanent establishment or tax residence in Portugal that carry out VAT-taxable transactions.
• Stamp Duty: Submit the Monthly Stamp Duty Declaration (DMIS) electronically by taxable persons responsible for acts, contracts, documents, securities or other transactions subject to Stamp Duty, including exempt transactions, carried out during the previous month.

The interpretation expressed herein is not intended to standardize the interpretation and application of tax and accounting rules and is therefore not binding on Moloni. Specialized professional advice should be sought for each of the matters addressed.