Portuguese VAT (IVA): monthly vs quarterly, deadlines, and the August rule

For the full month-by-month tax and legal calendar of a Portuguese Lda, see the tax and legal calendar (2026). For the detail of the two annual filings (Modelo 22 and IES), see the dedicated guide.

What is the periodic VAT declaration

The periodic VAT declaration is where a company reports, for each period, the VAT charged to clients (output VAT) and the deductible VAT paid to suppliers (input VAT), and settles the difference. If output VAT exceeds input VAT, the company owes tax to the State; if input VAT is higher, the excess becomes a VAT credit that is either carried forward or refunded, within the rules of the Código do IVA (CIVA).

The declaration is submitted electronically on the Portal das Finanças and, unlike the Modelo 22 and IES, does not require the certified accountant’s signature to be submitted (although in practice it is the accountant who prepares and files it). Payment is made separately, on the same portal, against a generated reference.

VAT rates in 2026: Mainland, Madeira, and the Azores

Article 18 of the CIVA sets three rates per region, chosen based on the type of good or service (the CIVA annexes define, in detail, what falls under the reduced, intermediate, and standard rates):

The lower regional rates in the Azores and Madeira are provided for in article 18(3) of the CIVA as compensation for the costs of insularity and outermost-region status. For cross-region transactions (for example, a mainland company invoicing a client in the Azores), the CIVA and Portaria 292/2011 set out which rate applies and where the transaction is located for tax purposes.

Quarterly vs monthly regime: how it is determined

Article 41 of the CIVA sets periodicity based on the prior calendar year’s turnover:

• Quarterly regime (default): prior-year turnover below €650,000. The declaration is filed four times a year.
• Monthly regime (mandatory): prior-year turnover at or above €650,000. The declaration is filed every month.

A taxpayer on the quarterly regime can opt in to the monthly regime before hitting the threshold. Following the reform introduced by Decree-Law 49/2025, the option remains valid until the taxpayer files a declaration to return to the quarterly regime (under article 32 of the CIVA), which takes effect from the same year if filed by the end of January. The reverse move (from monthly to quarterly, having been on monthly by obligation and then dropping below the threshold) has its own CIVA rules.

Regime change since 1 July 2025

Before July 2025, when a company’s turnover crossed the €650,000 threshold, the Tax Authority automatically switched it from quarterly to monthly. Since Decree-Law 49/2025 came into force (1 July 2025), the logic has flipped: it is now the company that must file a change declaration (declaração de alterações) during January of the year following the threshold crossing, to formalize the change to monthly.

Practically, for a Portuguese Lda whose 2025 turnover crossed €650,000: by 31 January 2026 the change declaration should have been filed, with the company on monthly regime from 1 January 2026. If it was not filed in time, non-filing is itself an infraction, and the AT can enforce the change ex officio with retroactive effect to the same date.

The accountant handles this filing, but it is worth confirming internally: an unformalized threshold crossing can mean missing monthly declarations and corresponding fines.

Filing and payment deadlines in 2026

The general rule, in article 41(1) of the CIVA:

• Filing of the periodic declaration: by the 20th day of the 2nd month after the tax period (monthly or quarterly).
• Payment of assessed VAT: by the 25th day of the same month.

For 2026, with the AT’s 2026 Agenda Fiscal and weekend/holiday shifts, the specific dates are:

Quarterly regime (2026)

Monthly regime (2026)

Each declaration is filed by day 20 of the 2nd month after, with payment by day 25. The one for June 2026 falls under the August rule and shifts to September:

• January 2026 → filing by 20 Mar; payment by 25 Mar.
• February 2026 → filing by 20 Apr; payment by 27 Apr (Monday, shifted from Saturday 25).
• March 2026 → filing by 20 May; payment by 25 May.
• April 2026 → filing by 22 Jun (Monday, shifted from Saturday); payment by 25 Jun.
• May 2026 → filing by 20 Jul; payment by 27 Jul (Monday, shifted from Saturday 25).
• June 2026 → filing by 21 Sep 2026 (August rule); payment by 25 Sep.
• July 2026 → filing by 21 Sep (same date after shift); payment by 25 Sep.
• August 2026 → filing by 20 Oct; payment by 26 Oct.
• September 2026 → filing by 20 Nov; payment by 25 Nov.
• October 2026 → filing by 21 Dec (Monday, shifted from Sunday); payment by 28 Dec (Monday).
• November 2026 → filing by 20 Jan 2027; payment by 25 Jan 2027.
• December 2026 → filing by 22 Feb 2027; payment by 25 Feb 2027.

Specific dates each year can shift slightly for weekends, holidays, and the official calendar. The AT Agenda Fiscal is the reference to check before each critical date.

The August rule: why June and Q2 jump to September

The CIVA provides for an automatic extension of VAT deadlines that fall in August. In practice:

• On the monthly regime, the declaration for June (which would otherwise be due on 20 August) is filed by 20 September (the statutory rule), with payment by 25 September.
• On the quarterly regime, the declaration for the 2nd quarter (which would otherwise be due on 20 August) is filed by 20 September, with payment by 25 September.

In 2026 the actual dates shift: because 20 September 2026 is a Sunday, the June (monthly) and Q2 (quarterly) declarations are filed by 21 September 2026 (Monday); the payment date remains 25 September (Friday). The table in the previous section reflects these shifts.

The pragmatic reason for the August rule is to accommodate the summer break: in August, companies, accountants and the AT itself operate with reduced teams. The extension prevents a purely seasonal spike in late-filing fines.

VAT credits and refunds

If, in a period, deductible VAT exceeds output VAT, there is a VAT credit. Two routes:

• Carry the credit forward to the next period. Most common approach for small or recurring credits.
• Request a refund from the AT. Applies above certain amounts and depends on the company’s situation. The CIVA and subsequent regulations set out when a refund can be requested, AT review timelines, and the conditions under which refunds may be deferred or offset against other tax debts.

The refund request is made on the periodic declaration itself; the AT can request additional documentation before processing the refund.

Consequences of filing or paying late

The Portuguese Regime Geral das Infrações Tributárias (RGIT) distinguishes two types of infraction:

Late or missed filing of the periodic VAT declaration. Article 116 of the RGIT sets a fine of €150 to €3,750 per missed declaration. As explained in the dedicated guide on Modelo 22 and IES, for legal persons article 26(4) of the RGIT doubles the limits, so €300 to €7,500 applies in practice to a Portuguese Lda.

Late payment of the assessed VAT. Article 114 of the RGIT sanctions the late or missed payment of tax, distinguishing intent (dolo) and negligence:

• Intent (dolo): the fine ranges from the value of the unpaid tax up to double that value (article 114(1)).
• Negligence: the fine ranges from 15% to half (50%) of the unpaid tax (article 114(2)).

When the infringer is a legal person, article 26(4) of the RGIT doubles the minimum and maximum fine limits in the applicable legal offence types.

On top of the fine, the unpaid tax accrues default interest (juros de mora) under article 44 of the Lei Geral Tributária (LGT), running from the end of the voluntary payment period until regularization.

Reduced fine for voluntary regularization. Article 30 of the RGIT allows the fine to be reduced to 12.5% of the legal minimum provided that, cumulatively: (i) no formal notice, complaint, or denunciation has been drawn up and no inspection is under way; (ii) the AT notifies the reduced fine based on the regularization; and (iii) payment is made within 30 days of that notification. Regularizing immediately, before any notification, opens this window.

Practical routine

Five points to stay on top of VAT deadlines:

1. Alert at the start of each month. Day-20 filings and day-25 payments require preparation. An alert five to seven days out leaves room for small corrections.
2. Close accounts for the period on time. The periodic declaration presupposes the period’s invoicing and expenses are closed. Keeping the books current month by month avoids last-minute scrambling.
3. Watch the August rule. June (monthly) and Q2 (quarterly) filings jump to September. It is easy to mistake this for a “rest period”; the workload piling up for September is real.
4. Track turnover annually. Approaching €650,000 means preparing the switch to monthly regime. Since 2025, the change declaration is the taxpayer’s responsibility, not the AT’s.
5. Save the receipts. Every filing and every payment generates an electronic receipt. Banks, lenders and potential buyers request them often.

In Limitada, VAT filing and payment deadlines live in the calendar shared with the accountant, with alerts before each obligation, and receipts are stored in the Company Card next to the rest of the company’s tax documentation. See Limitada.

This article is for information only. Specific dates each year should be confirmed against the Agenda Fiscal published annually by the Tax Authority. To prepare, correct, or regularize your company’s periodic VAT declaration, consult the certified accountant responsible for the company’s bookkeeping.