If you've just moved to France and you're staring at the tax system wondering where to begin — this is where you begin. A plain-English overview of how France taxes you, what's different from the UK, and what you need to know before you touch a single form.
- France has two separate charges on income — income tax and social charges — and you need to understand both before you start filling in boxes
- As a French tax resident you must declare your worldwide income — including UK income you've already paid UK tax on
- France calculates tax on the whole household, not on individuals — your partner's income and family size directly affect your bill
- The S1 certificate is the most important variable for most UK expats — it determines whether you pay full social charges, reduced charges, or nothing at all
The French tax system catches UK expats off guard in three main ways: it has two separate charges not one, it taxes your worldwide income, and it calculates everything on a household basis rather than individually. Once you understand those three things, the rest follows.
For the practical filing process, see our guide to filing French taxes as a UK expat — it covers the Plan, Map, File approach to getting your return done.
There Are Two Separate Taxes in France
This is the single most important thing to understand. When you live in France, you are subject to two separate charges on your income:
1. Income Tax This works like the UK system — a sliding scale with bands. The more you earn, the higher the rate on the top portion of your income. The 2026 brackets run from 0% up to 45%. See the income tax brackets on the Taxpert reference data page →
2. Social Charges This is where France differs significantly from the UK. On top of income tax, France levies a second charge — currently up to 18.6% in 2026 — on certain types of income. This funds France's healthcare system, debt repayment, and social security. It is separate from income tax, calculated differently, and the rate you pay can vary depending on your circumstances.
When you add the two together, the combined burden on some types of income can be substantial. This is why understanding both charges — not just income tax — matters.
There is also a flat rate option for investment income — the flat tax at 31.4% in 2026. We cover that separately below.
France Taxes Your Worldwide Income
If you are tax resident in France, you are required to declare your worldwide income — regardless of where it was earned and regardless of whether you have already paid tax on it in another country.
This surprises many UK expats. You may have a UK pension being paid to you with UK tax already deducted. France still requires you to declare it.
This does not necessarily mean you pay tax twice. France has double taxation agreements with many countries — including the UK — which determine which country has the right to tax each type of income. Some income is taxed only in France. Some is taxed only in the source country. Some attracts a tax credit in France to offset what was paid abroad.
But the declaration obligation exists regardless. You declare everything, and the treaty rules determine what you actually owe.
For a full explanation of how the France-UK treaty works and which income types it covers, see our guide to how the France-UK double tax treaty works.
The France Individual DT Form — Stop Paying UK Tax at Source
If you have UK-source income — a State Pension, a private pension, interest, royalties — there is an important form you need to know about early on.
The France Individual DT form instructs HMRC to stop deducting UK income tax from your payments at source. Once you are a French tax resident, most UK-source income should be paid to you gross — with tax paid only in France.
Here is how it works:
- Complete the form — providing details of your UK income sources
- Send it to your local French tax office — they certify it with a stamp to confirm you are a French tax resident
- Send the certified form to HMRC — HMRC then instructs your pension provider or bank to pay you gross
This is generally a one-time process. Once HMRC has issued the no-tax code, you do not need to resubmit annually — unless your circumstances change.
If you are filing in France for the very first time: the starting point is Cerfa 2043 — the form used to obtain your French tax identification number. You need this number before you can file anything.
Your Tax is Calculated on a Household Basis
In the UK, income tax is assessed individually. In France, it is assessed on the whole household — and this changes things considerably.
Every household is divided into shares:
- A single person = 1 share
- A married or civil partnership couple = 2 shares
- Children = 0.5 shares each for the first two, 1 full share for the third and beyond
How the calculation works:
- Your total household income is divided by your total number of shares
- The income tax bands are applied to that per-share figure
- The tax for one share is then multiplied back by your total shares to get your bill
In practice, this means couples benefit from wider effective tax bands than a single person on the same income. If one partner earns significantly more than the other, dividing the combined income across both shares reduces the rate applied to the higher earner's income.
For a full explanation see our quotient familial guide.
Income Tax and Social Charges Are Separate Calculations
Although they appear on the same annual declaration, income tax and social charges are calculated separately — treat them as two distinct things.
Income tax is always based on the sliding scale, adjusted for your household shares.
Social charges depend on two things: the type of income, and your healthcare status.
- If you hold an S1 certificate — issued by the UK, certifying you are covered by the UK healthcare system — you are exempt from French social charges on pension income, or pay a significantly reduced rate on investment income
- If you do not hold an S1, you pay social charges at rates that depend on your household reference income from two years prior
This distinction is important enough that the S1 question should be the first thing you answer before completing any part of your return. For a full explanation, see our S1 guide — what it is, who gets one, and why it matters.
For the current social charges rates by income type and S1 status, see the social charges rates on the Taxpert reference data page →
A Note on Investment Income — The Flat Tax
If you have interest, dividends, or capital gains from securities, these are subject to a separate flat tax — currently 31.4% in 2026 (12.8% income tax + 18.6% social charges).
You can choose to opt out of the flat tax and have this income taxed instead under the sliding scale — by ticking box 2OP on your return. This is worth considering if your income tax rate is 0% or 11%, as the sliding scale may result in a lower overall charge.
Ticking box 2OP is a global, all-or-nothing decision — it applies to all investment income across your entire household.
For more information see PFU vs progressive tax: which is better for your investment income.
When Do You File?
The French tax year runs from 1 January to 31 December — the same as the UK calendar year.
If you arrive in France part way through the year, you declare the income you received from your arrival date onwards — not the full year.
Filing deadlines open around 1 May each year. The closing date depends on your department number and is usually in late May or June. Check the deadline for your specific department on impots.gouv.fr — filing late attracts penalties.
The most common mistake with the timeline: people think they have until the end of June regardless of where they live. The deadline is staggered by department. Check yours specifically.
Common Mistakes in Understanding the French Tax System
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Thinking you only declare French income. You declare worldwide income. Always. The treaty rules determine what you owe — but the declaration obligation applies to everything.
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Treating income tax and social charges as the same thing. They are calculated separately, at different rates, with different rules about exemptions. Understanding both is essential before you start filling in boxes.
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Not knowing about the France Individual DT form. Many UK expats spend years having UK tax deducted at source unnecessarily. This form stops that — but you have to know it exists and submit it.
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Filing as if you were an individual. France files by household. Your partner's income, your children, your household composition all affect your final bill. You cannot work out your liability by looking at your own income alone.
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Missing the department-specific filing deadline. The deadline is not the same for everyone. It is staggered by department number and published each year. Check yours.
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Not getting a tax identification number before your first return. If it is your first time filing in France, you need a French tax identification number first. Get this via Cerfa 2043 before anything else.
Where to Go From Here
This is the foundation. Every other article on this site assumes you understand what is explained here.
The natural next steps, in order:
- How the France-UK double tax treaty works — which country taxes which income types
- The S1 explained — your healthcare status and how it affects your social charges
- Income type guides — pensions, rental income, dividends, interest — each covered separately
Or if you are ready to work out your numbers: Taxpert's filing assistant will import your income, convert currencies at the correct Banque de France rates, and produce a filing-ready summary with the correct form sections indicated.
Frequently Asked Questions
Do I have to declare income I've already paid UK tax on?
Yes. As a French tax resident you are required to declare your worldwide income — including income that has been taxed in the UK. This does not mean you pay tax twice. The France-UK double taxation agreement determines which country has the right to tax each income type. But the declaration obligation in France applies regardless.
What is the difference between income tax and social charges?
Income tax is a sliding-scale charge on your overall household income — the rate increases as income rises, similar to the UK. Social charges are a separate charge, currently up to 18.6% in 2026, applied to certain types of income. They are calculated differently and the rate you pay can be reduced or eliminated depending on whether you hold an S1 certificate.
What is the household shares system?
France calculates tax on the whole household rather than on individuals. Your total household income is divided by the number of shares assigned to your household — 1 for a single person, 2 for a couple, with additional shares for children. This means couples and families benefit from lower effective tax rates than a single person on the same total income.
What is the France Individual DT form and do I need it?
If you have UK-source income — a State Pension, private pension, interest, or royalties — the France Individual DT form instructs HMRC to stop deducting UK tax at source and pay you gross. It is completed once, certified by your local French tax office, and sent to HMRC. If you are receiving UK income with UK tax being deducted and you are a French resident, you almost certainly need this form.
When do I need to file my French tax return?
The French tax year runs 1 January to 31 December. Filing opens around 1 May each year. The deadline varies by department number — usually late May to late June. Check the deadline for your specific department on impots.gouv.fr each year. Filing late attracts penalties.
I just arrived in France — what do I do first?
Three things, in this order. First, obtain your French tax identification number via Cerfa 2043 if you don't already have one. Second, complete the France Individual DT form if you have UK-source income, to stop UK tax being deducted at source. Third, start keeping records of all income from your arrival date — that is what you will declare on your first French return.