2026 Tax season in spain: a guide to avoiding common mistakes

The 2026 tax season in Spain is set to begin on April 8, with taxpayers having until June 30 to submit their declarations to the Tax Agency. The first step is accessing the draft declaration, a preliminary document created by Hacienda to facilitate the process.

However, submitting the draft without reviewing it is a critical error that could lead to lost money. The reason is that Hacienda may make mistakes in its creation. As the document is based on personal, family, and economic data available at a certain point, it may not reflect reality. If your situation has changed, the tax authorities may not know it.

Key points to check before giving the 'OK' include personal and family data, work income, extra earnings, regional deductions, and tax benefits for contributions. Special attention should be paid to boxes 435 and 460 of the 100-R model.

Box 435: the general taxable base

Box 435 represents the general definitive taxable base, on which the IRPF tax rates are applied after deductions. This amount is obtained by summing up net work income, property income (rents), business income, and certain non-transactional capital gains.

Box 460: the taxable base of savings

Box 460 groups the earnings from investments, such as interest, dividends, and the net balance of capital gains and losses (sales of shares, properties, etc.) during the fiscal year. It is crucial to review this box as it determines the taxation of savings and affects certain deduction limits.

To avoid errors in the 2026 tax return, it is essential to carefully review the draft declaration before submission. The tax authorities can impose penalties for failing to declare the 'Casillas 435 and 460' bonus, which are critical fields in the model 100-R declaration.

To correct mistakes in the draft declaration, access the document in Renta Web, review the information point by point, and edit the incorrect data before confirming. Once modifications are made, save the changes and return to the 'Summary of Declarations' to see if the result (to pay or to be refunded) has changed. It is recommended to test different scenarios, such as individual or joint declarations, to determine the most favorable option.