March 2026 Tax Obligations for Companies in Portugal
March is a particularly demanding month for companies in Portugal. In addition to recurring VAT, withholding tax and Social Security obligations, this period concentrates important deadlines related to 2025 income tax, deduction validation and specific declarations. We've prepared this guide so you don't miss any deadline.
Early March - Until March 2
Deadlines falling in the first days of the month.
02 Mar - Invoice Validation on e-Fatura (IRS 2025)
Last day to validate 2025 expense invoices on the e-Fatura portal. Since the usual February 28 deadline falls on a weekend, the limit is extended to March 2. This includes classifying health, education, housing and professional activity expenses for all household members.
Category: IRS
02 Mar - Household Update
Deadline to report changes in household composition (marriage, divorce, birth, changes in dependent custody) on the Tax Authority portal, for 2025 income tax purposes.
Category: IRS
02 Mar - Model 10 Declaration
Deadline for submitting Model 10, regarding income paid to resident taxpayers not included in monthly remuneration declarations (DMR). Covers taxable, exempt or non-taxable income, as well as respective withholding taxes.
Category: IRS / IRC
Until the 5th - Invoice Communication
05 Mar - Invoice Communication to AT (VAT)
VAT taxable persons must electronically communicate to the Tax Authority the elements of invoices issued in February 2026, or declare their non-issuance. This is a monthly obligation applicable to all companies and professionals with registered activity.
Category: VAT
Until the 10th - Remunerations and Social Security
10 Mar - Monthly Remuneration Declaration (DMR) - AT
Submission of the Monthly Remuneration Declaration for February 2026 to the Tax Authority. Applicable to all employers, including individuals with employees.
Category: IRS
10 Mar - Remuneration Declaration - Social Security
Submission of the remuneration declaration for February 2026, exclusively through Social Security Direct. In 2026, companies can voluntarily join the new Social Security Declaration regime.
Category: Social Security
From the 16th - Tax Deductions
16 Mar - Tax Deduction Consultation and Complaint (IRS 2025)
From March 16, taxpayers can consult the tax deductions calculated by the Tax Authority for 2025 income tax on the Finance Portal. If there are omissions or incorrect values, complaints can be submitted until March 31.
Category: IRS
Until the 20th - Withholdings, VAT and Stamp Duty
20 Mar - IRS/IRC Withholding Taxes
Submission and payment of IRS and IRC withholding taxes made in February 2026. Covers income categories A (employment), B (business and professional), E (capital) and F (rental).
Category: IRS / IRC
20 Mar - Periodic VAT Declaration - Monthly Regime
Taxable persons under the normal monthly periodicity regime must submit, via Internet, the periodic declaration for VAT assessed in January 2026, together with respective annexes.
Category: VAT
20 Mar - Recapitulative VAT Declaration
Mandatory submission for monthly regime taxable persons who have made intra-community supplies of goods or services to taxable persons in other Member States in February 2026.
Category: VAT
20 Mar - Monthly Stamp Duty Declaration (DMIS)
Electronic submission of the declaration and payment of Stamp Duty settled in February 2026.
Category: Stamp Duty
Until the 27th - VAT Payment
27 Mar - VAT Payment - Monthly Regime
Last day to make the VAT payment assessed in the periodic declaration for January 2026, for taxable persons under the monthly periodicity regime.
Category: VAT
Until the 31st - End of Month
31 Mar - Tax Deduction Complaint (IRS 2025)
Last day to complain about omitted or incorrect tax deductions calculated by the Tax Authority on the Finance Portal, for 2025 income tax.
Category: IRS
31 Mar - IRS and VAT Consignment
Deadline to opt for the consignment of 1% of IRS or VAT to a social, cultural or sports entity, at no additional cost to the taxpayer.
Category: IRS / VAT
31 Mar - IUC Payment - March Registrations
Last day for payment of the Single Vehicle Tax (IUC) for 2026, for vehicles whose registration anniversary falls in March.
Category: IUC
31 Mar - Model 30 Declaration - Non-Resident Income
Entities owing or paying income to non-resident taxable persons in Portugal must submit Model 30 regarding income paid or made available in January 2026.
Category: IRC
March Summary in Numbers
A month with high density of tax and declarative obligations. Plan ahead to avoid fines and delays.
- 15+ Obligations
- 7 Key dates
- 6 Taxes
💡 Your Group Tip
Remember that when a deadline falls on a weekend or holiday, the obligation can be fulfilled on the next business day. The late payment interest rate set by AT in 2026 is 6% per year. Delays can result in fines, suspension of tax benefits, blocking of VAT refunds and difficulties in accessing credit and financing. Stay ahead and keep your company compliant.
⚠️ 2026 Update - IRC Rate
The general IRC rate decreased to 19% from January 1, 2026 (previously 20%), with plans to reach 17% by 2028. SMEs and Small Mid Caps benefit from a reduced rate of 15% on the first €50,000 of taxable income. The national minimum wage increased to €920 gross per month.
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