With the arrival of each new Income Tax campaign, thousands of taxpayers face a process that, although repeated year after year, continues to generate doubts and, above all, errors. From incorrectly entered data, omitted deductions, to late-filed returns, errors are more common than you might think. And the worst part is that they can end up being very expensive.
Making mistakes on your tax return can not only mean paying more tax or receiving a smaller refund, but it can also lead to serious financial penalties, surcharges, and even tax audits. The good news is that most of these errors can be avoided with a proper review, up-to-date knowledge, and, if necessary, timely corrections to your return. For more information on this process, you can consult our guide on how to file your tax return.
Most common mistakes when filing your income tax return
Among the most common errors detected in taxpayer returns, there are several that, despite their apparent simplicity, can have significant financial consequences.
- Failure to review tax dataMany people accept the draft provided by the Tax Agency without checking it. This document is generated with information provided by third parties (companies, banks, etc.), so it may contain errors. If it is submitted as is and there are errors, the responsibility falls on the taxpayer. It is essential not to skip this step to avoid problems related to the income tax return errors.
- Forgetting to include additional incomeSome people fail to declare odd jobs, rent, bank interest, or subsidies. These oversights can lead to penalties if the Treasury detects the omitted income.
- Do not apply available deductions: There are numerous deductions (for children, mortgage, rent, disability, etc.) that many people are unaware of or do not apply correctly, paying more than necessary.
- Declare without being obliged or thinking that you are not obligedNot all citizens are required to file a tax return, but many are overconfident. For example, if you have had more than one payer with an income exceeding €15.876 per year, you are obliged to declare.
- Submit lateLeaving everything to the last minute and not filing on time can result in late fees. These can range from 1% to 15%, plus late payment interest if more than a year has passed.
How to correct errors after filing a return
If you've noticed a mistake after submitting your tax return, there are ways to fix it . All is not lost, but it's crucial to act as soon as possible to avoid surcharges or more serious penalties.
Errors that harm the Treasury
If you discover that you've paid less than you should have or received more refund than you were entitled to, it's best to file an amended tax return . This type of return allows you to correct errors such as undeclared income, improper deductions, or mistakes that unfairly benefit the taxpayer. For more details on this type of return, you can visit the amended tax return page.
The supplementary return is submitted from the "Modify filed return" section on Renta WEB. You must provide the correct information and the reason for the adjustment. The Treasury calculates the difference between the previous and new returns, applying the corresponding surcharge if filed late.
Errors that harm the taxpayer
If you realize you've overpaid or received a smaller refund than you were entitled to, you can request a correction of your self-assessment . This means you don't need to file a supplementary return, but rather ask the Tax Agency to amend the return in your favor.
This includes cases such as:
- Omission of tax deductions or reductions.
- Include exempt income as if they were subject to taxation.
- errors in declared amounts.
The request for rectification must be processed within the legal period of four years from the end of the voluntary filing period. It is done through the same Renta WEB platform and, if applicable, the Tax Agency will refund the difference along with late payment interest.
What happens if you didn't file a return when you were required to?
If you failed to file your tax return and were required to do so, it's best to do it as soon as possible , even if the deadline has passed. If the tax authorities detect the omission and issue a request for information, the penalties will be higher.
- If the declaration was to be enteredA 1% surcharge plus an additional 1% for each month of delay will be applied up to the first year. After 12 months, the surcharge will be 15% plus late payment interest.
- If it was to be returned, they can impose a fine of 100 euros (reducible to 60 if you do not appeal and pay quickly).
Most common fines and penalties for errors in the declaration
The Tax Agency considers different types of penalties depending on the severity and nature of the error:
- Minor errors: Incomplete or incorrect data without financial loss is usually penalized with 100 to 200 euros, if the Treasury detects the error before you do.
- Undue deductions: If you apply a deduction that does not apply to you, the fine may be 15% of the amount improperly requested.
- Use of false documents:Using fake invoices or inflating expenses to deduct more can result in penalties ranging from 50% to 100% of the related amount.
- Frauds exceeding 3.000 eurosThe Treasury can impose fines of up to 150% of the amount defrauded. In serious cases, the fine can exceed €300.000.
- Errors with the NIFA minor error with the tax identification number can result in a fine of 150 euros, but a serious one can result in a fine of 30.000 euros.
Who is responsible if the manager made the mistake?
Even if you've hired a tax advisor or manager, you, as the taxpayer, remain ultimately responsible to the tax authorities . If the error was the advisor's fault, you can file a civil or criminal claim against them, but the tax authorities will require you to correct the error and pay the corresponding penalty, unless you have formally identified the advisor as responsible for the tax return. That's why it's important to avoid mistakes when investing and filing your tax return.
In cases where the manager has committed fraud or manipulated information, they may even incur criminal liability, with penalties that could include imprisonment if the amount exceeds 120.000 euros.
What if the error is from previous years?
It is also possible to submit a supplementary return or a rectification request for prior fiscal years within the four-year limitation period from the last day of the voluntary filing period.
If the deadline has passed, it's no longer necessary to amend the return, as the tax authorities can no longer make claims and the taxpayer can no longer demand refunds. Therefore, now is the time to review for any potential errors , before it's too late.
Thoroughly reviewing your tax return, understanding available deductions, filing on time, and correcting errors as soon as possible are fundamental steps to avoid unnecessary expenses. Although the Tax Agency has become more lenient with penalties for minor errors, serious mistakes still have significant consequences . It's advisable to stay informed about tax changes each year, use official tools like Renta WEB, and if you have any questions, consult a tax advisor to help you avoid unpleasant surprises.
