You are a French tax resident, you work in Switzerland, and you are covered by LAMal (Swiss compulsory health insurance) rather than the French regime. On your capital gains, dividends, interest and rental income, that makes you exempt from French CSG-CRDS and social charges, which is up to 18.6% you can keep.
The catch is that the tax office applies the full flat tax by default, 31.4% since 2026 (30% before). To switch the exemption on you have to tick box 8SH on form 2042. Miss it and you pay contributions you do not owe. Here is who qualifies, what it is worth, and where the box lives.
Background: the de Ruyter ruling
Before 2015, France applied CSG-CRDS to every French tax resident, including people covered by another European social security regime. The Court of Justice of the European Union, in the de Ruyter ruling of 26 February 2015, held that a contributor cannot be subject to the social charges of two Member States at once. So if you pay into a social security regime in the EEA, Switzerland or the United Kingdom, and are not covered by a French regime, you are exempt from CSG (9.2%) and CRDS (0.5%), a 9.7% break.
Since 2019, the solidarity levy has also been excluded from the legal definition of social contributions, so it does not apply either to people covered by a foreign regime under this ruling. Out of the 18.6% of French social charges (the 2026 rate), the 9.7% of CSG-CRDS is exempt through box 8SH, and the remaining 8.9% (the solidarity levy and the rest) is excluded too, also via box 8SH. That is 18.6% saved on all your investment income.
Watch the timing: before 2019 only the 9.7% of CSG-CRDS was exempt and the solidarity levy remained due. Today the exemption covers the full 18.6% in most cases, but case law and tax doctrine move. Confirm your exact situation with a tax advisor.
Who can tick box 8SH?
You need all three of these to be true: you are a French tax resident filing a 2042, you are covered by a mandatory social security regime of another EEA State, Switzerland or the United Kingdom, and you are not covered by a French mandatory regime. The typical case is a France-Switzerland cross-border worker on LAMal who chose Swiss cover rather than French CMU/PUMA when the option came up.
If you opted for French CMU/PUMA, you do not get the exemption: you are on a French regime and still owe the full CSG-CRDS.
1French tax resident
You file a 2042 return in France.
2Covered by a foreign regime
A mandatory social security regime of another EEA State, Switzerland or the UK. LAMal counts.
3Not on a French regime
Having opted for CMU/PUMA closes the door, even while working in Switzerland.
Box 8SH is open
Up to 18.6% less in social levies on your capital income.
The conditions are cumulative: one missing is enough to close the box. The third eliminates the most cases, because it depends on a choice made when the option came up, often years earlier.
What income is covered?
The exemption applies to all capital income declared in France: securities capital gains (selling shares, ETFs or holdings on a French CTO), dividends and coupons (unless already taxed at source in Switzerland), real-estate capital gains on a French property, rental income from a French property, and interest on non-regulated savings and term deposits.
Life insurance and the PEA are a special case, with their own tax regimes. The exemption still applies but the calculation differs; see our article on ETF taxation in France.
Real impact on a CTO
Say you realise +€50,000 of capital gains on your French CTO.
| Regime | Rate | Tax | Net |
|---|---|---|---|
| Standard PFU (resident without LAMal, since 2026) | 31.4% | €15,700 | €34,300 |
| Standard PFU (pre-2026 income) | 30% | €15,000 | €35,000 |
| Cross-border LAMal (8SH ticked) | 12.8%* | €6,400 | €43,600 |
* With the full 18.6% of social charges exempt, only the 12.8% PFU income tax remains. The treatment of the solidarity levy for foreign-regime affiliates can still evolve, so confirm your own case.
That is about €9,300 more in your pocket than a standard French resident in this example (€6,400 in tax instead of €15,700), from ticking one box.
The IgniFI copy-trading simulator lets you see both regimes side by side on a real backtest: pick "Cross-border LaMal" in the CTO taxation section to see the effect on your PnL.
Where is box 8SH?
On the online declaration at impots.gouv.fr, at the section-selection step tick "Securities income" and "Investment income" as they apply. Then go to page 4 of form 2042, to the section for investment income exempt from social contributions (CSG-CRDS), and tick box 8SH: investment income exempt from social contributions for people affiliated with a social security regime of another EEA State, Switzerland or the United Kingdom. If you are a couple and both qualify, also tick 8SI for the spouse.
Keep your LAMal card or proof of affiliation to the Swiss regime (S1 form or an attestation from your sickness fund). The tax office can ask for justification.
If you missed the box in past years
You can ask for a retroactive correction within the standard claim window, until 31 December of the second year following the assessment. For a 2023 declaration on 2022 income, for instance, you have until 31 December 2025.
Log into impots.gouv.fr, go to secure messaging, choose to write to your tax office and report an error in the calculation of your tax, then attach your LAMal proof and ask for boxes 8SH and 8SI to be corrected for the years concerned. Refunds of social charges collected in error usually land within two to four months. Over five years of meaningful gains, that can be several thousand euros.
Common mistakes
Ticking 8SH while on French CMU/PUMA is the worst one, because the administration cross-checks with URSSAF and the reassessment comes with late interest. Forgetting 8SI for a spouse who also works in Switzerland on LAMal is common. So is failing to keep the LAMal proof, since without it the exemption is removed in an audit. Remember the box does not replace the declaration: you still report your gains normally (boxes 3VG and 3VH) and additionally tick 8SH to signal the social regime. And it is not automatic just because you work in Switzerland; it is LAMal affiliation that creates the right, so if you chose French CMU you pay the full 18.6%.
Recap
A cross-border worker on LAMal ticks 8SH, plus 8SI for the spouse where relevant. A cross-border worker on French CMU/PUMA gets no exemption and leaves it unticked. The retroactive claim deadline is 31 December of the second year after the assessment. The saving runs up to 18.6% on all your French capital income (against the 31.4% PFU since 2026), and the proof to keep is your LAMal card or S1 attestation.
For foreign-account reporting (Switzerland, eToro, IBKR and so on), see our guide on declaring foreign accounts in France: forms 3916, 2047 and obligations.
This article is informational and is not personalised tax advice. The cross-border situation keeps evolving (the de Ruyter ruling, successive PLFSS, tax doctrine), so for significant amounts consult an accountant or a tax lawyer specialised in international mobility.