Form 2042: the complete guide (annexes, dates, pitfalls)
The 2042 is THE French income tax return: salaries, family, tax reductions. Prefilled data covers the basics, but the money-saving boxes (actual expenses, donations, PER, 2OP) and the annexes (2042 C, 2047, 3916) are up to you.
What prefilled data doesn’t do for you
Salaries, pensions and most French bank income arrive prefilled. Everything else is on you: actual expenses vs the 10% allowance, donations, alimony, retirement savings (box 6NS for the PER), box 2OP, student and apprentice exemptions — and each of these boxes can be worth hundreds of euros.
Prefilled data can also be wrong: check every amount against your documents (last payslip of the year, bank statements) before submitting.
The common annexes
2042 C: the “complementary” boxes — foreign income with tax credit (8TK), micro-entrepreneurs, SME investment…
2047: mandatory as soon as any income comes from abroad (cross-border salary, pension, foreign dividends).
3916 / 3916-bis: one per foreign account (bank, neobank, crypto platform), with box 8UU.
2044: rental income under the real regime (above €15,000 of rent or by option).
Online, everything is activated at the start under “Déclarations annexes”.
The 2027 dates to remember
The online return historically opens in the second week of April, then closes between late May and early June depending on your département (three zones). Paper closes before online. Our calendar keeps the dates up to date and can email you when filing opens.
Frequently asked questions
Nothing to fix in the prefilled data: do I still need to file?
Some households get automatic filing (no action needed if nothing changed). But with actual expenses, donations, a PER, foreign accounts or non-prefilled income, actively filing is essential — and that’s where the savings are.
Can I fix things after submitting?
Yes: online you can amend until the deadline, then via the correction service open from summer to mid-December. After that, a formal claim remains possible.