In summary…
September is the last moment when decisions are still being made. In December, decisions are no longer made: what remains possible is executed, within the deadlines that others — banks, notaries, insurers — allow.
Four questions frame the exercise: where will your last euro of income go?, How much retirement savings ceiling is actually left?, what does the wallet contain in latent, And What needs to be launched now because its execution time exceeds the remaining time?.
The most frequent answer to these four questions is that there is nothing to do this year. That's one answer, and it's often the right one.
The exercise takes place from January 1st to December 31st, but it can only be managed between September and the end of November. Before that, the revenue is unknown; after that, the execution times have consumed the window. Hence, four questions, in this order: each one conditions the next.
1. Where will your last euro of income go?
The marginal rate, not the average rate
All year-end tax adjustments are calculated based on the tax rate applied to the last euro taxed, never on the average rate, which only measures past expenses. The tax scale in Article 197 of the French General Tax Code (CGI) is progressive and adjusted by the family quotient: two households with the same income do not have the same marginal tax bracket.
The question is therefore not "how much will I earn", but where does my projected income end in the scale?. For a manager, this means stopping remuneration and dividends for the last quarter early; for a professional, it means a profit forecast, not a current revenue figure.
Specifically. An exceptional income changes everything: compensation, price supplements, or back payments from several years all raise the marginal tax rate in a single fiscal year. This is the year when the deduction is most valuable, and the year when the quotient applicable to exceptional or deferred income is examined first, since it modifies the tax base. Conversely, a lean year is a bad year for deductions.
2. The retirement savings limit, including any remaining balances
And the point at which the euro paid ceases to be profitable
This limit is not a fixed annual figure, but rather a cumulative total: the current year's limit is added to any unused allowances from the three previous years, and the limits for a couple filing jointly can be combined. The actual available amount is shown on the tax assessment notice.
The only question that matters is: at what euro does the investment cease to be profitable? It doesn't yield a stated rate; it yields the marginal slice that he erases. As soon as it brings the household back down into the lower bracket, subsequent euros only produce the savings of that bracket — and the exit will be imposed in a situation that is not yet known.
Specifically. An unused allowance isn't lost immediately: it lasts for three years, making waiting possible. Waiting only incurs a cost on the oldest remaining allowance, the one that expires at the end of the fiscal year. (Knowledge) what portion of your ceiling expires this year is the only information that makes the September decision rational.
For the technician. Article 163 quatervicies of the CGI: deduction from net total income of retirement savings payments, within a limit based on the professional income of the previous year, with a floor for low or zero income; carry-forward of the unused ceiling for three years, consumption of the ceiling of the year before the oldest remainders, pooling between spouses subject to joint taxation.
The payment is assessed upon its actual receipt, not on the date of the order: a transfer made on December 29th to a plan yet to be opened falls under the following financial year, with the ceiling of the following financial year.
3. What the wallet contains in latent
Capital losses can only be offset against gains of the same nature.
In a securities account, capital losses are offset against capital gains of the same nature in the same year, and then, for the remaining balance, against those of the following ten years. They are never offset against total income: they do not reduce a salary, business profits, or rental income.
A stock of carryforward capital losses is therefore a tax asset that expires. And a capital gain already realized opens a window, until December 31st, to realize unrealized capital losses and neutralize all or part of the gain. This window does not reopen in January.
For the technician. Article 150-0 D of the French General Tax Code (CGI): Capital losses on the sale of securities and equity interests can be offset against capital gains of the same nature in the same year, with any remaining balance carried forward for ten years. The offset is applied to gross gains, before any applicable allowances—which has a significant impact on older securities.
The PEA (Equity Savings Plan) operates on a different principle: capital losses recorded within the plan are not transferred to this account, except upon closure and under the specified conditions. The sale followed by the immediate repurchase of the same securities requires careful attention to the legitimacy of the transaction.
4. What needs to be launched now
Because the execution time exceeds the remaining time
This is the most overlooked issue and the only one that is truly irreversible. Certain transactions take effect on a date beyond your control: payment to the insurer, signing of the deed, transfer of a plan, closing of a sale. Changing a matrimonial property regime follows the timeline of Article 1397 of the Civil Code—notarial deed, notification of adult children and creditors, objection period, and approval in the cases provided for. This is the procedural timeline, not the client's.
- Opening a retirement savings plan — Subscription, onboarding, payment collection. Only payment collection matters, and it doesn't depend on you.
- Transfer of an existing plan — Inter-institutional instruction, divestment, reinvestment. Not to be confused with an annual payment.
- Notarized gift — Assessment, draft deed, formalities. The tax recovery for previous gifts is calculated from date to date, so a few weeks' delay pushes everything back by a year.
- Transfer of securities or business — Audit, negotiation, conditions precedent, closing. Launched in September, it is rarely signed before the following financial year — sometimes the objective.
- Change of matrimonial regime — It's measured in months, never weeks. Nothing can be made up for in December.
What not to do
The council is also judged by the transactions it refuses.
Every autumn, the same proposals circulate: last-minute payments presented as tax savings, tax-oriented subscriptions whose underlying assets have never been examined, and arbitrage justified solely by the proximity of December 31st. None of them are backed by an income forecast—no one has done so.
A tax-deductible contribution ties up cash until retirement or a specific withdrawal event, and creates a future tax liability at an unknown rate. The deduction is not a gain, it's a deferral—and a deferral is only worthwhile if it moves from a higher to a lower tax rate. In a low tax year, the transaction has a negative value.
Four questions. If even one remains without a quantified answer, the review has not taken place.
Do you know your projected taxable income as of December 31st, and which tax bracket it falls into? What portion of your retirement savings limit expires this year? Does your portfolio contain unrealized losses and a capital gain that needs to be realized? And of the transactions you're considering, which ones require more time than you have left?
Our position
Many years pass without any surgery.
A well-executed back-to-school review most often ends with a decision to do nothing: income in line with expectations, spending limit not expiring, portfolio with nothing to clear, no major transactions pending. All that remains is to write one page—the one explaining why, which will be reviewed the following year.
Years requiring action are recognizable by a single signal: something exceptional is either entering the fiscal year or will be leaving the next. A sale, compensation, a release of funds, a departure. This is where September matters, and it's the timing, more than the outcome, that decides.
Are you unsure of your progress with your current exercise?
The first meeting is used to answer the four questions and to decide: what we launch before the end of September, what we decide in November, what we don't do. Forty-five minutes, without obligation — and if there is nothing to do, we say so on the way out.
Are you a chartered accountant, notary, broker or fellow consultant? The review combines projected results, private assets, and the timeline of actions. We work in a joint venture, and the client remains yours.
Make an appointment
Thirty minutes to calculate your tax bracket exit point, with your latest tax assessment in front of you. If the answer is that you don't owe anything, we'll tell you that too.
