The delivery of the IRS declaration for 2025 income once again marks one of the most sensitive moments of the tax year for Portuguese families. Despite the generalization of automatic IR and pre-filling on the Finance Portal, the margin for error remains significant and, in many cases, translates into overpaid tax, lower refunds or subsequent notifications from the Tax Authority. The central theme is simple but decisive: validate each field before pressing “send”.
According to , which cites the Federal Revenue and Customs, a relevant part of the discrepancies detected every year arise from lapses that could have been avoided with a careful review of the declaration before delivery.
The starting point that must not fail
The first check must concern the framing of the declaration itself. The 2026 IRS exclusively concerns income earned between January 1 and December 31, 2025, but it is not uncommon to find declarations submitted based on drafts from previous years. An error of this kind jeopardizes the entire qualification.
Next comes the title page, which is often underestimated. Data such as tax residence, household composition and marital status on December 31st are decisive for calculating the tax. A change of address, an unconsidered marriage, divorce or separation can significantly alter the final result.
Updating the household deserves particular attention. Dependents, ascendants and shared custody situations must be correctly identified and consistent with the information provided by the other parent. Small inconsistencies can lead to the loss of relevant deductions.
Where most errors and money losses arise
The choice between joint or separate taxation remains one of the most delicate points for couples. Choosing out of habit, without simulating both scenarios, could mean giving up a more favorable tax result, especially when there are significant differences in income between the two taxpayers.
Another source of error is related to blind acceptance of the automatic IRS. Although useful, the system is only based on information available to the IRS at the time, which may exclude tax benefits, occasional income or recent changes in personal or professional situation.
Checking the annexes is also essential. Salaries and pensions must be included in Annex A, self-employment in Annex B, rent in Annex F, capital gains in Annex G and income obtained outside of Portugal in Annex J. Any omission may lead to discrepancies and delays in reimbursement.
Also declaring bank accounts abroad continues to elude many taxpayers. Even without associated income, identification is mandatory. The same applies to the verification of withholding taxes, which must coincide with the annual receipts from paying entities.
Simulating remains the best defense
Before final delivery, simulation remains one of the most effective tools to avoid surprises. Testing different scenarios allows you to evaluate, for example, whether the inclusion of interest, dividends or property income pays off in the face of autonomous taxation. In many cases, seemingly small differences have a real impact on the final amount payable or received.
Tax deductions require equal care. Expenses for health, education, housing and general family expenses must be correctly classified in the e-Fatura. Anyone who chooses to manually fill out Annex H must do so with particular care, as this choice implies the automatic replacement of the values calculated by the Federal Revenue Service.
According to the same source, a complete review of the declaration before submission significantly reduces the risk of subsequent corrections and ensures that the final IR calculation actually corresponds to the tax situation of each taxpayer.
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