leclairon, Those are the income tax bands and not related to the RFR. There is a different calculation for the RFR.
2OP only refers to the way unearned income, interest/capital gains/dividends, is taxed and has no effect on pensions or other earned income taxation.
I don't know of a free calculator available online for PFU and I don't know whether those which are available from some companies if you sign up, e.g.
https://www.cacomptepourmoi.fr/blog/gui ... rogressif/ will include foreign income, etc?
The full calculation of income tax can get quite complicated as there are various allowances and additional charges which are made. Foreign government pensions/associated tax credits add other complications. I developed my own spreadsheet to check my tax, as I didn't find the annual statement very clear(!), but the spreadsheet only covers my income sources and isn't generally applicable. There is a full method of tax calculation in the last sections of the official guide which is published annually. The current guide is the Déclaration des revenus 2023 Brochure pratique brochure 2024 which is also downloadable as a 434 page PDF
www.impots.gouv.fr/www2/fichiers/docume ... ccueil.htm
But, in the simplest form to understand, and excluding any of the allowances, etc., they add up the total household income and divide by the number of "parts" in the household, two for a couple. That figure is used to calculate the tax for that part according to the tax scale (for one person) and that tax is then doubled for the household. That means the overall tax can be at a lower rate than if just the tax band was use.
The scale is
Up to €11,294 0%
From €11,295 to €28,797 11%
From €28,798 to €82,341 30%
From €82,342 to €177,106 41%
More than €177,106: tax rate of 45%
This page gives various worked examples of the tax scales
https://www.service-public.fr/particuli ... 19?lang=en
2OP only refers to the way unearned income, interest/capital gains/dividends, is taxed and not pensions or other earned income.
If you tick 2OP your interest/capital gains/dividends is just added in to your overall income figure and the tax calculated as above using the tax scales (and if you tick 2OP there are abattements for some forms of income).
If you do not tick 2OP your interest/capital gains/dividends are taxed at the flat rate of 12.8%.
If, when you do the above rough tax scales calculation, the figure for the total income (earned and unearned) for a single part in the household is still within the 0% or 11% tax bands you should tick 2OP. That is probably why many francophile web sites/guides recommend ticking as there is an assumption the total income is not likely to be high enough to be taxed in the 30% band.
Ticking 2OP may reduce the total tax bill if your unearned income, interest/capital gains/dividends, would take a single part into the 30% income tax band, but it becomes a complicated calculation unless a long way into the band.