The Renta 2025 campaign is entering its final countdown. After almost three months of filing declarations, the tax calendar is heading towards its closure with two dates marked in red: June 25, the last day to direct debit the payment of declarations with a result to be paid, and June 30, the date on which the IRPF campaign officially concludes.
But the end of the deadline does not mean the end of the process for all taxpayers. For those who have not filed their declaration on time or have not correctly paid the corresponding amount, a less friendly second phase begins: that of tax authority requests, popularly known as the “fear letters.”
The expression has become popular to refer to the notifications that the Tax Agency sends when it detects non-compliance, errors, or pending payments in the declaration. They are not an anomaly of the system, but rather one of the usual control tools of the Tax Agency once the campaign expires. Receiving one does not always imply an immediate penalty, but it does mark the beginning of a review or procedure that may end in surcharges, fines, or adjustments.
Late Declarations
The context is not minor. This year's Renta campaign, corresponding to income obtained in 2025, started on April 8 and the Tax Agency expects to receive a total of 25.25 million declarations. However, at the end of May, just over 15.2 million had been filed, leaving nearly 40% of taxpayers still pending to comply with this tax obligation with only one month left until the deadline. In other words, millions of taxpayers have reached the final stretch without having yet completed the process, a scenario that each year triggers last-minute rushes and multiplies the risk of errors, omissions, or late filings.
In that context, TaxDown, a Spanish company specializing in digital tax advisory, reminds DEMÓCRATA that not filing the declaration on time can be costly even when the taxpayer decides to regularize their situation on their own initiative. If the declaration results in a payment due and Hacienda has not yet sent any requirement, the surcharge is 1%, to which another 1% additional is added for each full month of delay. Thus, filing the Income Tax in July would mean a 1% surcharge; doing so in August, 2%; in September, 3%; and so on. When more than twelve months have passed, the surcharge amounts to 15%, in addition to late payment interest.
The situation worsens when the Tax Agency has already made a move and sent the corresponding requirement. In these cases, the so-called "fear letters" can lead to penalties of between 50% and 150% of the amount that has not been paid. The regulations do, however, contemplate reductions on this penalty if the taxpayer shows conformity and pays on time without appealing. Even so, the economic cost and administrative burden increase considerably compared to a voluntary regularization.
Not filing the declaration is not free either when the result is not a payment due. If the Income Tax results in a refund or zero quota and the taxpayer does not file it within the deadline, Hacienda can also impose a penalty. In these cases, the fine amounts to 100 euros if there has been no prior requirement and 200 euros if the Tax Agency has already sent a notification demanding the filing.
It's not just about filing: it's also about paying correctly
The risk of receiving a notification from Hacienda does not only affect those who miss the deadline without filing the declaration. It can also affect those who do file on time, but do not complete the payment correctly when the result is a payment due. An error in the IBAN, insufficient balance in the account, or any incident in the direct debit can leave the debt unpaid and subsequently activate the claim procedure.
In these cases, if the taxpayer detects the error and pays voluntarily, the surcharge is 5% on the outstanding amount. If, on the other hand, the Tax Agency sends the request first alerting of non-payment, that surcharge can increase and be between 10% and 20%. That is why experts recommend not only filing the return within the deadline, but also checking that the payment has been executed correctly and that there have been no errors in the bank account or in the payment method chosen.
June 25, a key date for those who have to pay
One of the most relevant milestones in this final stretch is June 25, the last day to direct debit the payment of the return if it results in an amount due. From that date, the taxpayer will still be able to file the Income Tax Return until June 30, but will no longer be able to charge the first installment to an account via direct debit. In that case, they will have to opt for other methods: direct debit only the second installment, pay the amount in a single payment by means of a payment document, pay by card or Bizum, or request installment or deferral options depending on their situation.
This detail is not minor, especially for those who rush to file until the last days. The closure of direct debiting forces a change in the payment method and can generate incidents if the taxpayer does not carefully check which option they are selecting or assumes that the charge will be made automatically.
The Tax Agency can review the Income Tax Return up to four years later
Beyond the closing of the campaign, experts remind us that the return is not protected once it has been filed. The Tax Agency has a period of four years to review a self-assessment and check if the declared data is correct. This means that the so-called "fear letters" can arrive not only in July, at the end of the campaign, but also months or even years later if the Tax Agency detects inconsistencies, undeclared income, incorrectly applied deductions, or lack of documentary justification.
"It is important to highlight that the Tax Agency has up to four years to review Income Tax Returns, so it is possible to receive one of these letters even several years after the current campaign ends. That is why we always recommend keeping all documentation that proves the information we are declaring in order to justify our data in the future as well," explains to DEMÓCRATA Aitor Fernández, tax expert at TaxDown.
With the calendar already in its final phase, the underlying message for taxpayers is clear: it is not enough to file on time; it is also advisable to review the draft in detail, check that the result is correct, validate the chosen payment method, and keep all supporting documentation. Because when the campaign closes its doors on June 30, for many the less visible, but also more delicate, part of the relationship with the Treasury will begin.