Introduction: The Strategic Importance of the 2026 Tax Calendar for Business Management

Navigating the complex Portuguese tax landscape demands precision, planning, and a deep understanding of legal obligations. For any entity, be it a small or medium-sized enterprise (SME) or a large corporation, timely and rigorous compliance with its tax responsibilities is not merely a matter of legal conformity, but a critical component of its financial health and market reputation. Delays in submitting declarations, omissions of information, or late payments not only incur financial penalties in the form of fines and late payment interest, but can also compromise the company's image with the Tax and Customs Authority (AT) and other stakeholders.

The year 2026, like any other, presents a set of challenges and opportunities regarding tax management. This exhaustive guide has been meticulously prepared to serve as a compass, guiding accountants, managers, and entrepreneurs through the most relevant tax deadlines. Organised logically and chronologically, it covers everything from the most frequent monthly obligations to annual and ad-hoc ones, with the aim of facilitating robust financial planning and ensuring full compliance with current legislation. Anticipation and organisation are, in this context, the keys to avoiding unpleasant surprises and optimising the tax burden, allowing companies to focus on their core business with the peace of mind that their tax responsibilities are properly safeguarded.

1. Monthly Tax and Contribution Obligations: The Pillar of Continuous Compliance

Monthly obligations form the backbone of tax and contribution compliance. Their regularity demands constant attention and well-defined internal processes to ensure no deadline is overlooked.

1.1. VAT - Value Added Tax: Cash Flow Management and Compliance

Value Added Tax (VAT) is one of the most dynamic taxes with the greatest impact on companies' cash flow. Its efficient management is crucial.

• Monthly Regime (applicable to companies with a turnover exceeding €650,000 in the previous calendar year, or those that opt for this regime):
• Submission of the Periodic Declaration: By the 20th of the 2nd month following the period to which the operation relates. This declaration details the VAT charged and deductible.
• VAT Payment: By the 25th of the 2nd month following the period to which the operation relates. The amount payable corresponds to the difference between the VAT charged and the VAT deductible.
• Practical Example (Monthly Regime): VAT relating to operations carried out in January 2026 must be declared by 20 March 2026, and if there is tax to pay, payment must be made by 25 March 2026. A delay of just one day in payment, for example, would entail the application of late payment interest and fines.

Legal basis: Articles 41 and 27 of the Value Added Tax Code (CIVA).

1.2. IRS and IRC Withholding Tax: The Responsibility of the Tax Substitute

Entities paying income subject to withholding tax act as tax substitutes, having the responsibility to withhold the tax and remit it to the State.

• IRS/IRC Withheld: The declaration and payment of amounts withheld at source (whether IRS on salaries, fees, rents, or IRC on specific income) must be made by the 20th of the month following that in which the income was paid or made available.
• Payment Slip: Submission is made electronically through the Tax Portal, using the appropriate payment slip model (e.g., Model P2 for IRS/IRC).

Legal basis: Article 98 of the Personal Income Tax Code (CIRS) and Article 94 of the Corporate Income Tax Code (CIRC).

1.3. Social Security: Contributions and Declarations

Social security is a pillar of the social protection system, and compliance with contribution obligations is vital for employers and employees.

• Remuneration Declaration (DMR): Must be submitted by the 10th of the month following that to which the remunerations relate. This declaration communicates to Social Security the salaries paid and contributions due.
• Payment of Contributions: The period for payment of contributions runs between the 10th and 20th of the month following that to which the remunerations relate.
• Single Social Tax (TSU): The TSU is composed of the employer's contribution (23.75% of the wage bill) and the employee's contribution (11% of their gross salary). It is essential to correctly calculate these percentages to avoid discrepancies.

Legal basis: Code of Contributory Regimes of the Social Security System (Law No. 110/2009, of 16 September, and its amendments).

1.4. Invoice Communication (SAF-T): Transparency and Control

The communication of invoice elements to the AT is a measure to combat fraud and tax evasion.

• Communication: The elements of invoices issued in the previous month must be communicated to the AT by the 5th of the following month. However, there is a tolerance that allows communication until the 8th working day of the following month, without the application of penalties.
• Format: Communication is carried out via the SAF-T (PT) invoicing file, in XML format, in accordance with the technical specifications of Ordinance No. 302/2016, of 2 December.

2. Quarterly Obligations: Periodic Management and Simplification

Quarterly obligations are particularly relevant for SMEs and for companies with intra-community activities.

2.1. VAT - Quarterly Regime: Administrative Relief for SMEs

This regime is an option for companies with an annual turnover of up to €650,000 (a limit that can be updated annually). It offers relief in the frequency of obligations.

• 1st Quarter (January to March): Periodic Declaration by 20 May; Payment by 25 May.
• 2nd Quarter (April to June): Periodic Declaration by 20 August; Payment by 25 August.
• 3rd Quarter (July to September): Periodic Declaration by 20 November; Payment by 25 November.
• 4th Quarter (October to December): Periodic Declaration by 20 February of the following year; Payment by 25 February of the following year.

2.2. Recapitulative Statement (Intra-Community Transactions): Single Market Control

Essential for companies that carry out transactions of goods or services with other European Union Member States.

• Deadline: The Recapitulative Statement must be submitted by the 20th of the month following the quarter to which the transactions relate.
• Mandatory for: Intra-community supplies of goods and services to VAT taxable persons in other Member States, when the place of supply is that of the acquirer (reverse charge mechanism).

Legal basis: Article 29 of the VAT Regime for Intra-Community Transactions (RITI), approved by Decree-Law No. 290/92, of 28 December.

3. Annual Obligations: The Fiscal Year Balance Sheet

Annual obligations are important milestones in tax management, consolidating information for an entire year.

3.1. Model 22 - Corporate Income Tax Periodic Declaration: The Annual Accounts

Model 22 is the main Corporate Income Tax declaration for most companies, where the fiscal result for the year and the tax due are calculated.

• Deadline: The submission of Model 22, referring to the 2025 fiscal year, must be made by the last working day of May 2026 (which corresponds, in 2026, to 29 May, if 31 May is a Sunday or holiday, or 31 May, if it is a working day).
• Exercise: Refers to the immediately preceding fiscal year. In the case of 2026, the declaration relates to the 2025 exercise.
• Payment: The payment of the calculated Corporate Income Tax, after deduction of payments on account and withholding taxes, is made by the same deadline for submitting the declaration.

Legal basis: Article 120 of the CIRC.

3.2. IES/DA - Simplified Business Information / Annual Declaration: A Multifaceted Obligation

The IES/DA is a complex declaration that brings together information from different entities, simplifying the fulfilment of various obligations.

• Deadline: For entities with a fiscal year coinciding with the calendar year, the deadline for submitting the IES/DA for the 2025 exercise is 15 July 2026.
• Content: The IES/DA aggregates the submission of various information, including:
  • Annual declaration of accounting and tax information for the AT (Submission of SAF-T (PT) accounting files, balance sheet, income statement).
  • Statistical elements for the National Institute of Statistics (INE).
  • Information for the Bank of Portugal (BP).
  • Registration of accounts filing acts at the Commercial Registry Office.

Legal basis: Decree-Law No. 8/2007, of 17 January, and Ordinance No. 208/2012, of 6 July.

3.3. Model 10 - Income and Withholding Declaration: The Annual Summary

This declaration consolidates the withholding taxes carried out during the previous year.

• Deadline: The submission of Model 10, referring to withholding taxes made in 2025, must be carried out by 10 February 2026.
• Content: Annual summary of all income subject to withholding tax (IRS and IRC) paid or made available, as well as the taxes withheld, itemised by beneficiary. This information is crucial for filling in the beneficiaries' income declarations.

3.4. Model 30 - Declaration of Income Paid to Non-Residents: International Taxation

Mandatory for entities that pay income to non-residents in Portugal.

• Deadline: The declaration and payment (if applicable) must be made by the end of the 2nd month following that in which the payment or making available of the income occurred.
• Mandatory for: Income such as royalties, interest, dividends, services, rents, among others, paid or made available to non-resident entities or individuals in Portuguese territory, subject to withholding tax at a final rate or on account, in accordance with the CIRC, CIRS or double taxation treaties.

Legal basis: Article 123, No. 1, paragraph c) of the CIRC, and Ordinance No. 367/2014, of 22 December.

4. Corporate Income Tax Payments on Account: Tax Anticipation

Payments on account aim to anticipate the payment of Corporate Income Tax due at the end of the financial year, contributing to the stability of State tax revenues.

Payment	Deadline	Amount
1st Payment on Account	By 31 July 2026	33% of the Corporate Income Tax assessed in the previous year (2025).
2nd Payment on Account	By 30 September 2026	33% of the Corporate Income Tax assessed in the previous year (2025).
3rd Payment on Account	By 15 December 2026	34% of the Corporate Income Tax assessed in the previous year (2025).

Legal basis: Article 104 of the CIRC.

Practical Example (Payments on Account): A company assessed Corporate Income Tax of €15,000 in the 2025 financial year. The payments on account for 2026 would be:

• 1st Payment on Account: €15,000 * 33% = €4,950 (to be paid by 31 July).
• 2nd Payment on Account: €15,000 * 33% = €4,950 (to be paid by 30 September).
• 3rd Payment on Account: €15,000 * 34% = €5,100 (to be paid by 15 December).

It is important to note that companies can suspend or reduce payments on account if they estimate that the Corporate Income Tax due at the end of the financial year will be less than the total amount of payments on account. However, this decision should be taken with caution, as an underestimation can lead to penalties.

5. Other Specific Obligations and Deadlines: Relevant Details

In addition to the most common obligations, there are other deadlines that may apply depending on the company's activity and characteristics.

5.1. Inventory Communication: Transparency and Stock Control

Entities that hold inventories are obliged to communicate the valuation of their goods to the AT.

• Deadline: The communication of the inventory referring to the last day of the financial year (31 December 2025) must be made by 31 January 2026.
• Format: Communication is made via a file, with structure and content defined by Ordinance No. 2/2015, of 5 January.

Legal basis: Article 3-A of Decree-Law No. 198/2012, of 24 August.

5.2. Model 39 Declaration - Capital Income: Financial Transparency

This declaration is intended to communicate capital income subject to final withholding tax rates.

• Deadline: By the end of February of the year following that to which the income relates.
• Mandatory for: Debtor entities or those paying capital income subject to definitive withholding tax (final tax rates), such as deposit interest, dividends, etc.

5.3. Special Payment on Account (PEC): A Specific Feature for Corporate Income TaxThe PEC is an annual payment that companies subject to Corporate Income Tax must make, although there are increasingly more exemptions.

• Deadline: As a rule, it is paid in two instalments, in March and October, or in a single payment in March, if the amount is less than €1,000. For the 2026 financial year, the dates would be 31 March and 31 October.
• Calculation: The PEC is calculated based on the turnover of the previous period, with a minimum of €850 and a maximum of €70,000. It is important to check the exemption conditions, which have been extended in recent years.

Legal basis: Article 106 of the CIRC.

6. 2026 Summary Calendar: An Overview

To facilitate quick reference, we present a summary of the main tax deadlines for 2026.

Month	Obligation	Deadline
January	Inventory Communication (2025)	31st
	VAT 4th Quarter (quarterly)	Declaration by 20th, Payment by 25th
February	Model 10 (2025)	10th
	Model 39 (2025)	28th (end of month)
March	1st PEC Instalment (if applicable)	31st
May	Model 22 (IRC 2025)	Last working day (approx. 29th/31st)
	VAT 1st Quarter (quarterly)	Declaration by 20th, Payment by 25th
July	IES/DA (2025)	15th
	1st Payment on Account (IRC)	31st
August	VAT 2nd Quarter (quarterly)	Declaration by 20th, Payment by 25th
September	2nd Payment on Account (IRC)	30th
October	2nd PEC Instalment (if applicable)	31st
November	VAT 3rd Quarter (quarterly)	Declaration by 20th, Payment by 25th
December	3rd Payment on Account (IRC)	15th
	Additional Payment on Account (PAC)	15th

7. Common Errors to Avoid in Tax Management

Even with a detailed calendar, the complexity of legislation can lead to mistakes. Identifying and preventing these errors is fundamental.

• 1. Late Submission of Declarations: This is the most basic and common error. Late submission, even by one day, incurs fines and late payment interest. It is crucial to have an alert and review system.
• 2. Failure to Communicate Invoicing on Time: Communication of the SAF-T invoicing file after the 8th working day of the following month generates significant fines, which can range from €200 to €10,000, depending on the company's turnover. Legal basis: Article 123 of the General Regime of Tax Infractions (RGIT).
• 3. Improper Deduction of VAT: Deducting VAT from expenses that are not directly related to the company's activity or that the law expressly prohibits (e.g., entertainment expenses, passenger vehicles not used for the main activity) is a serious error, which can lead to corrections and penalties.
• 4. Underestimation of Payments on Account: Although the suspension or reduction of payments on account is a legal option, an overly optimistic estimate of the fiscal result can result in a 10% penalty on the difference between the tax actually due and the amount paid, plus late payment interest.
• 5. Errors in Filling in the IES/DA: Given its complexity and the aggregation of information for different entities, errors in the IES/DA are frequent and can lead to discrepancies with the AT, INE or the Bank of Portugal, requiring rectifications and, sometimes, fines.
• 6. Lack of Knowledge of Tax Benefits: Failure to take advantage of tax incentive schemes, such as SIFIDE (Tax Incentive System for Business R&D) or RFAI (Tax Regime for Investment Support), due to lack of knowledge or planning, results in the loss of significant tax savings for the company.
• 7. Failures in Document Management: Failure to keep tax and accounting documents for the legal periods (generally 10 years) or their poor organisation prevents the company from defending itself in the event of a tax inspection, which can lead to the presumption of income and the application of fines.

8. Consequences of Non-Compliance: A Necessary Warning

Non-compliance with tax and contribution obligations has a direct and severe impact on the company's financial health and credibility.

• Late Payment Interest: Applicable to tax due and not paid on time. The late payment interest rate for 2026 is 4% per year (Ordinance No. 292/2003, of 8 April, updated annually). This amount is calculated daily from the day following the end of the payment deadline.
• Fines for Late Submission of Declarations: Fines vary depending on the type of declaration, the length of the delay, and whether the infraction is voluntarily regularised or detected by the AT. They can range from €30 to €22,500, depending on the severity and the tax in question. For example, failure to submit the Periodic VAT Declaration can result in fines of €150 to €3,750 (Articles 116 and 117 of the RGIT).
• Loss of Tax Benefits: Companies with a history of tax non-compliance may have tax benefits and incentives denied or revoked, even if they meet the other requirements. Tax regularity is a prerequisite for accessing many public supports.
• Aggravation of the Tax Situation: In cases of recidivism or serious infractions, the AT may carry out more in-depth inspections, resulting in tax corrections and higher fines.
• Joint and Several/Subsidiary Liability: In certain situations, managers or administrators may be held jointly and severally or subsidiarily liable for the company's debts to the AT or Social Security, putting personal assets at risk.

Practical Example (Fine for delay): A company should have paid €5,000 of Corporate Income Tax by 31 May 2026, but only did so on 30 June 2026.

• Number of days delayed: 30 days (June).
• Late payment interest: (€5,000 * 4% / 365) * 30 days = €16.44.
• Fine: If the infraction is voluntarily regularised and the delay is less than 30 days, the fine can be reduced. However, if detected by the AT, the fine can range from 10% to 50% of the outstanding tax, with a minimum of €25 and a maximum of €27,500 (Art. 114 of the RGIT). In this case, a minimum fine of €25 would be applied, but it could be much higher depending on the AT's action.

Conclusion: Proactivity and Planning as Keys to Fiscal Success

Compliance with the 2026 tax calendar is an ongoing challenge for companies in Portugal, but it is also an opportunity to demonstrate rigour, organisation, and responsibility. Ignoring or underestimating these obligations can have significant financial and reputational repercussions, compromising the sustainability and growth of the business.

The key to efficient tax management lies in proactivity and planning. Companies are strongly advised to:

• Implement an Internal Tax Calendar: Adapt this guide to your company's specificities, creating a calendar with alerts and responsible parties for each obligation.
• Automate Processes: Use management and accounting software that automates the generation of files (SAF-T) and the completion of declarations, minimising manual errors.
• Invest in Continuous Training: Accounting and finance teams must always be up-to-date on legislative changes.
• Collaborate Closely with Professionals: Maintain constant and transparent communication with your certified accountants and tax consultants, who can offer specialised and strategic guidance.
• Conduct Periodic Reviews: Carry out regular checks of your obligations and payments to identify and correct potential deviations in a timely manner.

Business success is not only measured by profitability, but also by the ability to operate within legal and fiscal parameters. By adopting a diligent and informed stance, your company will not only avoid penalties but also build a solid foundation for its future development. Do not leave tax management until the last minute. Plan, execute, and ensure compliance for a financially secure and prosperous 2026.

Recommended Action (Call to Action): For a more in-depth analysis of your specific tax obligations and to optimise your strategy, contact your certified accountant today or request a consultation with our tax specialists.

Legal Sources and References

• CIRC - Corporate Income Tax Code (Decree-Law No. 442-B/88, of 30 November, and its amendments), in particular Articles 104 (Payments on Account), 106 (Special Payment on Account) and 120 (Periodic Income Declaration).
• CIVA - Value Added Tax Code (Decree-Law No. 394-B/84, of 26 December, and its amendments), in particular Articles 27 (Payment Deadlines) and 41 (Periodic Declaration).
• CIRS - Personal Income Tax Code (Decree-Law No. 442-A/88, of 30 November, and its amendments), in particular Article 98 (Withholding Tax).
• RGIT - General Regime of Tax Infractions (Law No. 15/2001, of 5 June, and its amendments), in particular Articles 114 (Omissions or inaccuracies in declarations), 116 and 117 (Failure to submit declarations).
• Code of Contributory Regimes of the Social Security System (Law No. 110/2009, of 16 September, and its amendments).
• RITI - VAT Regime for Intra-Community Transactions (Decree-Law No. 290/92, of 28 December, and its amendments), in particular Article 29 (Recapitulative Statement).
• Decree-Law No. 8/2007, of 17 January (Creation of the IES/DA).
• Ordinance No. 302/2016, of 2 December (Technical specifications of the SAF-T (PT) invoicing file).
• Ordinance No. 2/2015, of 5 January (Structure and content of the inventory communication file).
• Ordinance No. 367/2014, of 22 December (Approves Model 30).

Last updated: January 2026