2025 Income Tax Return: Dates, How to File, and What You Need

With the arrival of April, one of the most important times of the year from a tax perspective begins: the 2025 Income Tax Filing Season. Every year, thousands of taxpayers make mistakes that can result in penalties, surcharges, or financial losses because they do not correctly apply deductions.

In this article, we clearly explain when to file your 2025 income tax return, how to file it, and what documentation you’ll need—so you can avoid problems with the tax authorities.

When is the 2025 tax return due?

The filing period for income tax returns begins on April 8 and ends on June 30.

It is important to note that this tax return pertains to income and tax information for the year 2025.

If you do not file your tax return by the deadline, the tax authorities may impose:

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• • surcharges

• • late payment interest

• • financial penalties

In addition, if the tax liability is due, the deadline for setting up a direct debit is June 25.

How to File Your 2025 Tax Return: Online, by Phone, or In Person

There are several ways to file the tax return:

Online
Available from April 8 through June 30. This is the fastest and most commonly used option.

By phone
Available from May 6 through June 30. Appointments must be made starting April 29.

In-person
From June 1 through 30, also by appointment (starting May 29).

Which option you choose will depend on the complexity of your tax situation. In many cases, seeking professional advice can help you avoid significant mistakes.

Check your tax information before filing your tax return

Before approving the draft, it is essential to review the tax data held by the Internal Revenue Service. This data is not always complete or may contain errors.

The following are commonly missing:

•  

• • additional income

• • grants or subsidies

• • regional tax deductions

• • cryptocurrency transactions or investments

Ultimate responsibility always lies with the taxpayer, not with the tax authorities.

What documents do you need to file your 2025 tax return?

Although the Tax Agency already has a lot of information on file, it’s a good idea to have the following on hand:

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• • ID and Personal Information

• • bank account number (IBAN)

• • company income statement

• • property information (property tax, cadastral references, rents)

• • proof of purchase or sale of stocks, cryptocurrencies, or real estate

• • mutual fund certificates

• • proof of financial assistance or grants

• • receipts or documents that allow for deductions

Keeping all this documentation organized can make the difference between overpaying and properly optimizing your tax return.

Common Mistakes on Tax Returns

Every year we see the same mistakes:

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• • Do not review the draft

• • failing to report secondary income

• • forget deductions

• • failing to update personal or family information

A small mistake could lead to an audit by the tax authorities.

Do you need help with your 2025 tax return?

At Martínez Caballero Abogados , we help individuals, self-employed professionals, and businesses file their income tax returns correctly, avoiding mistakes and maximizing their tax refund.

If you want to make sure your tax return is filled out correctly or need advice, you can contact our team, and we’ll review your case on an individual basis.