Preparing your Portuguese tax return starts with gathering the right information. An accurate filing depends on having complete records of your income, deductible expenses, and any transactions that may affect your tax position during the year.

Although the Autoridade Tributária e Aduaneira (AT) pre-populates parts of the annual IRS (Imposto sobre o Rendimento das Pessoas Singulares) return using information submitted by employers, banks, and other entities, taxpayers remain responsible for reviewing the data and ensuring that their Modelo 3 declaration is accurate before submission.

The documents you need will depend on your tax residency status, income sources, property ownership, and any tax reliefs or deductions you intend to claim.

Personal Information and Tax Registration

Before the IRS filing period begins, check that your personal details are correct in Portal das Finanças. Outdated information can delay the processing of your return or any tax refund due.

You should have access to:

• Your Portuguese Tax Identification Number (NIF)
• Login credentials for Portal das Finanças
• A valid identification document or passport
• Your current tax address registered with the AT

If your marital status, household composition, tax residency, or bank account details changed during the tax year, these records should also be updated before filing.

Employment Income

If you are employed in Portugal, your employer reports your earnings and tax withheld directly to the AT. Even so, you should compare the pre-filled information in your annual IRS return with your employment records to confirm that all figures are correct.

Keep copies of your:

• Annual income statement
• Tax withheld at source
• Social Security contributions
• Details of any taxable employment benefits

If you worked outside Portugal or received employment income from another country, retain the relevant foreign income statements as these may also need to be declared.

Self-Employment Income

Self-employed professionals and sole traders should maintain complete financial records throughout the tax year. Accurate bookkeeping makes it easier to prepare the annual return and supports the deduction of business expenses if the AT requests evidence.

Depending on your activity, you may need:

• Sales invoices and receipts
• Expense invoices
• VAT (IVA) records
• Accounting records
• Social Security payment records
• Business bank statements

The exact reporting requirements depend on whether you are taxed under the simplified regime or organised accounting.

Pension Income

Every pension received during the tax year should be supported by the relevant payment statements.

This may include:

• Portuguese pension income
• UK State Pension
• Occupational pensions
• Private pension schemes
• Overseas pension income

If you receive pensions from more than one country, the applicable Double Taxation Agreement (DTA) may determine how the income is taxed in Portugal.

Investment Income

Investment income should be supported by statements issued by financial institutions or investment platforms.

Typical examples include:

• Interest earned on savings
• Dividend income
• Capital gains from investments
• Investment fund distributions
• Brokerage statements
• Cryptocurrency transaction reports, which are taxable

Each category of investment income is subject to specific Portuguese tax rules, making accurate reporting particularly important.

Rental Income

Property owners should retain clear records of both rental income and allowable expenses throughout the year.

Relevant records include:

• Rental agreements
• Rent received
• Property management fees
• Maintenance and repair invoices
• Condominium charges
• Insurance premiums
• IMI (Municipal Property Tax) payments
• Other deductible property expenses

Maintaining complete records helps calculate taxable rental income correctly and supports deductions claimed in the annual return. This is particularly important when preparing rental income tax returns, where accurate reporting of both income and allowable expenses is essential. 

Property Sales and Capital Gains

If you sold property during the tax year, additional documentation will be required to calculate any taxable capital gain.

You should retain:

• Purchase deed
• Sale deed
• Evidence of acquisition costs
• Invoices for qualifying improvement works
• Estate agency fees
• Legal and notarial costs

These records help establish the property's acquisition value and deductible expenses when calculating capital gains tax.

Records Supporting Tax Deductions

Many personal deductions are automatically recorded through e-Fatura, but it remains your responsibility to confirm that the information is complete before submitting your IRS return.

Review expenses relating to:

• Healthcare
• Education
• General family expenses
• Housing expenses, where eligible
• Nursing home costs
• VAT-supported deductions

Where information is missing or incorrect, supporting invoices should be retained as evidence.

Foreign Income

Portuguese tax residents are generally taxed on their worldwide income. If you earned income outside Portugal, collect records for every overseas source before filing.

This may include:

• Foreign employment income
• Overseas pensions
• Rental income from foreign property
• Dividends
• Bank interest
• Capital gains

You should also retain evidence of tax paid abroad, as this may be relevant when claiming relief under an applicable Double Taxation Agreement.

Banking Details

If you are entitled to a tax refund, ensure that your bank account details registered with the AT are accurate. Incorrect information can delay payment even after your return has been processed.

Additional Supporting Evidence

Depending on your circumstances, you may also need documentation relating to:

• Disability status
• Tax credits or exemptions
• Changes in tax residency
• Court orders affecting tax obligations
• Previous tax assessments
• Inheritance or gift reporting obligations

Not every taxpayer will require these records, but they should be available if requested by the AT.

Final Checks Before Submitting Modelo 3

Before filing your Portuguese income tax return, confirm that:

• Your personal details are up to date.
• All Portuguese and foreign income has been declared where required.
• Tax withheld has been correctly reported.
• Eligible deductions have been verified through e-Fatura.
• Property transactions have been accurately recorded.
• Your bank account details are current.
• You have retained copies of all supporting records.

Although many fields are completed automatically, the taxpayer remains legally responsible for the accuracy of the information submitted.

When Professional Assistance Is Recommended

Preparing an annual IRS return is relatively straightforward when your income comes from a single Portuguese employer. The process becomes considerably more complex if you are a non-resident, receive overseas income, own rental property, sell Portuguese real estate, operate as a self-employed professional, or need to apply the provisions of a Double Taxation Agreement.

Professional advice helps ensure that your return is completed accurately, available reliefs are correctly applied, and your reporting obligations are fully met. At Portutax, we assist Portuguese residents, non-residents, expatriates, and international investors in preparing and submitting Portuguese tax returns, providing practical guidance tailored to each client's circumstances.

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