41.5 million tax households must declare their income between this Thursday, April 9, 2026 and the beginning of June. Even if the form is pre-filled, it can always contain errors or miss some information. This is why it is important to always check the information given by the tax authorities. A missing box or an inaccurate number can cost several hundred euros… enough to put a certain amount of pressure when it comes time to validate it.
There is a first basic reflex to have: compare the amount of pre-filled income with the net tax total of your last pay slip (for example, that of December 2025 if you worked in the same place all year). This number is your reference. If it does not match what the declaration displays, correct it before validating. Finally, certain oversights are known to be frequent: tax credits (childcare, personal services, energy renovation), actual professional expenses, alimony, donations to associations, but also the amount paid into the PER.
What the tax administration offers to help you
If your tax form is more complex or you are worried about making mistakes, several options exist, all free:
- Secure messaging on impots.gouv.fr, for ask your questions directly to your manager service or report an anomaly.
- 0 809 401 401 (non-premium rate, Monday to Friday from 8:30 a.m. to 7 p.m.): this year, tax agents can take control of your screen to guide you step by step. In 2025, 11.8 million calls were handled.
- A telephone appointment with an agent, to be booked using the “Contact and Appointment” button in your particular space.
- Public finance centers and France Services points: 5,016 reception points distributed in more than 3,060 municipalities, for face-to-face help.
- Allo Impôt (0 8000 65432): for complex situations, volunteer accountants respond free of charge on May 20, 27 and June 3 (9 a.m.-6 p.m.), and May 21, 28 and June 4 (9 a.m.-9 p.m.).
Online tools to help you with your tax form
For those who prefer to search for solutions online or be guided outside of administration, two platforms stand out. Climb (weareclimb.fr) is recognized as a trusted third party by the DGFiP: the platform analyzes your situation and identifies the tax advantages to which you are entitled. More recent, TaxCut offers an AI-based assistant, which prepares your return within 48 hours from your documents. In both cases, the basic tool is free. Getting in touch with an advisor costs money.
No rush however, you still have time before validating everything. Here are the deadlines: for departments 01 to 19 and non-residents: May 21. Departments 20 to 54: May 28. Departments 55 and beyond (DOM included): June 4. The paper declaration must be sent until May 19 for everyone. Keep in mind that an online declaration can be modified up to your department’s deadline. And even after, a correction service remains open from mid-August to mid-December 2026.
