Your Total French Tax Bill: A Worked Example Combining Income Tax and Social Charges (2026)

• Income tax and social charges are calculated on different bases, using different rules — but you only care about one number: what actually leaves your account
• This article combines both, across five real scenarios, to show the final bottom line — including a couple with mixed S1 status and the effect of electing the progressive scale
• The S1 certificate is the single biggest lever — it can roughly halve your total bill on pension income alone, and a mixed-status couple gets exactly that split, not a blended discount
• Mixing pension and investment income means combining two different calculation methods into one household total — this article shows exactly how that adds up, and when switching to the progressive scale is actually worth it

You already know France splits your tax into two separate calculations — income tax and social charges — each with its own rates, rules, and forms. What you actually want to know is simpler: what's the one number that leaves your account this year?

This article doesn't re-explain how each charge works individually — for that, see how the French tax system works and the social charges breakdown. What it does is combine them, on five realistic UK expat profiles, into a single bottom-line figure for each.

Scenario 1: Single person, UK private pension only, no S1

Profile: Single person (1 share), €30,000 gross UK private pension, no S1 certificate (based on RFR — standard 8.3% CSG band, see the RFR thresholds and rates here).

Scenario 2: The same person, but with a valid S1

Profile: Identical income, identical household — the only change is holding an S1 certificate.

The S1 alone takes this person's total bill from €4,435 down to €1,705 — a difference of €2,730, entirely from the social charges side. Nothing about the income tax calculation changes at all. This is why establishing your S1 status is the first practical step before any of these numbers mean anything for your situation — see the S1 guide.

Scenario 3: A couple with mixed income — pension and investments

Profile: Married couple (2 shares), no S1. Combined €40,000 UK private pension between them, plus €15,000 in dividend income from a UK investment platform, held in the standard CSG band.

This scenario mixes two different calculation methods on the same household return — the pension follows the progressive/social-charges-band route above, while the dividend income falls under the PFU flat tax at 31.4% (12.8% income tax + 18.6% social charges), unless they elect the progressive scale instead.

Pension side:

Investment side (under PFU, the default):

Combining for household income tax (2 shares):

Taxable pension (€36,000) ÷ 2 shares = €18,000 per share.

Tax per share (€715) × 2 shares = €1,430 income tax on the pension portion.

Full household total:

This is the kind of figure that's easy to underestimate when you only look at each income type in isolation — the pension feels manageable at roughly 13%, the dividends feel manageable at 31.4%, but the household total, blended across both income types and the quotient familial, lands at a different number than either piece suggests on its own.

Scenario 4: A couple where only one partner has an S1

Profile: Same married couple (2 shares), no investment income this time — just pensions. Partner A holds a valid S1 and receives €25,000. Partner B has no S1 and receives €15,000, falling (based on their own RFR — standard 8.3% CSG band, see the RFR thresholds and rates here) into the same 9.1% total social charges rate as Scenario 1. Combined household pension: €40,000 — identical total to Scenario 3, but split unevenly across S1 status.

Income tax doesn't care about S1 status at all, so the income tax side is calculated exactly as in any other €40,000 pension household. Social charges, however, only apply to Partner B's share.

Worth comparing this directly against the two single-person scenarios above: a fully S1-covered household paid €1,705 total (Scenario 2), a fully uncovered household paid €4,435 (Scenario 1), and this mixed household — with the same €40,000 split 62.5%/37.5% between S1 and non-S1 — lands proportionally in between, because social charges apply only to the non-S1 portion. The takeaway: a partial S1 household doesn't get a partial discount on the whole pot — it gets full exemption on one person's income and the full rate on the other's, and the household total reflects exactly that split.

Scenario 5: Does electing the progressive scale actually save money?

Going back to Scenario 3's couple — €40,000 pension, €15,000 UK dividend income, no S1 — what happens if they tick box 2OP to elect the progressive scale for the dividend income instead of accepting the default PFU flat tax?

What changes: under the progressive election, qualifying dividend income gets a 40% allowance before being added to other household income for income tax purposes. Social charges on the dividend income are unaffected by this election — they're still calculated on the full gross amount, at the same 18.6%, regardless of which option you choose. The election only changes how the income tax portion is calculated.

Note on this 40% allowance for UK dividends specifically: this allowance is well established for French-sourced dividends; treatment for foreign dividends can depend on the distributing company meeting certain conditions under French tax doctrine. This worked example assumes it applies — if you're relying on this for your own UK dividends, it's worth confirming with a tax advisor rather than assuming.

Compare that to Scenario 3's PFU total of €9,780 — electing the progressive scale saves this particular household roughly €929. The reason: their marginal income tax rate (11%, once combined and divided by shares) is well below the PFU's flat 12.8% income tax component, and the 40% allowance shrinks the taxable dividend amount further before that rate even applies.

This won't hold for every household. A higher earner whose marginal rate is 30% or more would generally do worse under the progressive election than the flat 12.8% PFU rate — the saving here is specifically a function of this household sitting in the 11% band. For the general decision framework, see the PFU vs progressive tax guide.

Why your own number will differ

These five scenarios use clean, round figures to make the mechanics visible. Your actual figure will move based on: your RFR band (which determines your CSG rate on pension income), whether you elect the progressive scale instead of the PFU for investment income, your exact household share count, and whether any portion of your income falls under a different treaty treatment (Government Service Pensions, for instance, follow an entirely different route — see the Government Service Pension guide).

The purpose of working through these scenarios isn't to give you your exact figure — it's to show you the shape of the calculation, so when you do work out your own numbers, you know which pieces to combine and in what order.

Frequently Asked Questions

Why don't income tax and social charges just get added together automatically?

They're calculated on different bases — social charges generally apply to gross income with no household-share adjustment, while income tax applies after allowances and is divided by your household shares. Combining them into one final number, as this article does, requires working out each separately first and then adding the results.

Does holding an S1 change my income tax, or just social charges?

Just social charges. The S1 exempts your pension income from CSG, CRDS, and CASA — it has no effect on the income tax calculation itself, which still applies based on your household's taxable income and share count.

If I have both pension and investment income, are they combined for the tax bands?

Pension income (after its allowance) gets combined with other progressive-scale income and divided by your shares for income tax purposes. Investment income under the PFU flat tax is calculated separately, at its own flat rate, and doesn't get blended into the household share calculation unless you elect the progressive scale for it instead.

My partner has an S1 but I don't — does our household get a partial discount?

No, not a blended discount. Each person's own pension income is assessed against their own S1 status — your partner's income is fully exempt from social charges, and your income is charged at the full applicable rate. The household total simply reflects whatever split exists between the two incomes.

Does electing the progressive scale for investment income always save money?

No — it depends on your household's marginal income tax rate once everything is combined and divided by shares. It tends to help households whose rate would otherwise sit at 0% or 11%, since that's below the PFU's flat 12.8% income tax component. Higher-rate households usually do better staying on the PFU. Run both numbers for your actual figures rather than assuming.

Is there a way to estimate this without doing it by hand every time?

Taxpert's filing assistant handles this calculation automatically — import your income sources and it works out the combined figure across pension, investment, and rental income together, based on your actual household details.