Can a taxpayer rectify a self-assessment that harms their legitimate interests?

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Yes. If a self-assessment has in any way harmed the taxpayer’s legitimate interests, the taxpayer may seek to have it corrected. First check the rules for the relevant tax and period: where those rules require a corrective self-assessment, the correction must be filed using the prescribed form. In other cases, the taxpayer follows the procedure for requesting rectification (Articles 120.3 and 4 of the Spanish General Tax Law, LGT).

For a rectification request, the original self-assessment must already have been filed. As a general rule, the request must be made before the tax authority issues a final assessment or its right to determine the tax becomes time-barred. A request cannot be made while an audit or verification procedure covering the same tax obligation is in progress. If a provisional assessment has already been issued, rectification is available only on grounds different from those addressed in that assessment (Article 126.2 and 3 of Royal Decree 1065/2007).

The tax authority has up to six months to notify its decision. If no express decision is notified within that period, the request may be treated as rejected for the purpose of bringing an appeal (Article 128.4 of Royal Decree 1065/2007). The former statement that the period was three months was incorrect.

If the correction gives rise to a refund, late-payment interest may be due under different rules depending on whether the refund arises under the tax rules or concerns an undue payment (Articles 120.3 and 32.2 LGT). If the correction only reduces the amount payable and does not create a refund, the taxpayer must still pay up to the corrected amount (Article 120.3 LGT).