Investing in the stock market has never been so accessible. In just a few clicks on a mobile application, any individual can become a shareholder in the giants of American Tech or the flagships of the CAC 40. However, investing involves a few tax traps which we must be wary of. The first ? Forget to declare each year your securities account or a trading account with a broker whose head office is located outside France or without a French branch. “ Hundreds of thousands of French people opened a stock market account in 2025 without realizing that they had just created an annual tax obligation for account holders abroad », declares Fabien Keryell, CEO of Saxo Banque. In case of forgetting? A fine of 1,500 euros. Worse still, if the account is not declared, the administration can invoke a special recovery period of ten years (instead of three), unless you prove that the balance has never exceeded €50,000. If you choose a broker regulated in France, you don’t have to do anything, they do it for you.
Another point of vigilance, do not confuse tax report and IFU. It is the latter, the Single Tax Form, form 2561, which is transmitted directly by the broker – subject to French regulations – to the tax authorities. Result ? Your boxes are pre-filled on your tax return. For foreign brokers, this is a simple tax report. It is then up to you to manually report each line, convert the currencies and verify the calculations. Watch out for typing errors…
Double taxation of foreign dividends
It’s the invisible tax that can eat into your return. When you receive dividends from foreign stocks (USA, Germany, Belgium, Switzerland, etc.), the country of origin may levy withholding tax. Then comes the French flat tax at the rate of 31.4% (article 200 A of the CGI). Without good management, you pay tax twice on the same income. Fortunately, tax treaties make it possible to obtain a tax credit to compensate for the tax paid abroad.
But be careful, getting it can be an obstacle course. First, the withholding varies depending on the country (Editor’s note: the list of tax conventions can be consulted on impots.gouv.fr). Then, the corresponding tax credit must be declared on form 2047 (income received abroad) and reported on form 2042. While some brokers automate this process, others leave investors alone with the calculations. “ This is money owed to the investor, he deserves help to get it back », declares Fabien Keryell.
The arbitration between flat tax and progressive scale
Since 2018, the default rule is single flat-rate deduction (PFU), the flat tax, at the overall rate of 31.4% (12.8% income tax + 18.6% social security contributions: rates applicable to capital gains made since January 1, 2025 and from January 1, 2026 for dividends and interest). But this is not always the optimal solution because for taxpayers whose marginal tax bracket is between 0 and 11%, the option for progressive scale (box 2OP) is often more advantageous. Be careful, however: this choice is global. You cannot choose the flat tax for your dividends and the scale for your capital gains; the option applies to all of your income from movable capital.
On the stock market, we don’t win every time but a loss can become a “tax asset”. According to article 150-0 D 11 of the CGI, your capital losses realized on an ordinary securities account (CTO) are attributable to capital gains of the same nature during the current year, and can be carried forward for ten years. How to benefit from it? It is imperative to declare them via form 2074, which involves knowing precisely the cost price and the selling price of each operation. “ A stock market loss is not just bad news, it is a tax credit which you can use for ten yearsspecifies Fabien Keryell. It is a legal, simple and too often lost optimization. “.
