8.12. Regularization of previous declarations
It may happen that, once the Income Tax return has been submitted, the taxpayer notices errors or omissions in the declared data. The procedure for rectifying such anomalies is different, depending on whether the errors or omissions have caused harm to the Public Treasury or to the taxpayer themselves.
SELF-ASSESSMENT CORRECTION: If the tax returns filed previously have been detrimental to the taxpayer, such as the omission of any deduction, the declaration of any exempt income, among others, the taxpayer may request the rectification of said return by means of a letter filed with the corresponding Administration or Office.
However, the program has incorporated a specific section to request the modification of self-assessments so that if box 127 of the rectification request is checked, the self-assessment acts as a request document.