Should at-source tax taken off savings be included in section 8 PAS boxes?

Are the payments of income tax and social charges on bank interest that I paid last year provisional in the same way that income tax pre-payments on pensions are? The total of my 12 monthly payments for the latter is pre-filled in my declaration in the section 8 boxes for prélèvement à la source but this does not include the 12.8% tax that I paid on bank interest. Also the section 8 box for pre-payments of social charges has not been pre-filled with the 7.5% social charges that I paid on bank interest. Should I modify the pre-filled figures to include my payments on bank interest?

There are two different issues here. 

Firstly, no, you should not add the tax and social charges taken from your French bank interest into the section 8 boxes.

The box 8HW is to show instalments of income tax taken out of your account in 2025 by direct debit based on your previous declarations. These levies are adjustable later with a refund or additional demands once your full income for 2025 is known after your declaration in 2026.

The amount in this box could relate, for example, to instalments of income tax on a UK pension that France is not able to directly tax at source. However, the tax and social charges taken at source on your French bank interest relate to the ‘flat tax’, officially called prélèvement forfaitaire unique (PFU). 

This is usually 12.8% income tax and 17.2% social charges, making a total of 30% (social charges are rising to 18.6%, thus total flat tax of 31.4%, from income received in 2026). You are presumably, as would be correct, paying social charges on your investment income at a reduced rate (7.5%) as you are a UK or EU state pensioner and not attached to the French social security system.

When taken off at source, the 12.8% income tax is technically an instalment and not definitive and will probably have been pre-filled in section 2, box 2CK of the main 2042 declaration. If you leave it there – or add it, if not pre-filled – it will become definitive as part of the overall PFU flat tax calculation for the year on investment income.

Alternatively, you can opt for taxation according to the ordinary tax bands by selecting box 2OP – be aware though that if you do this it will apply to all investment income for the year 2025. If you opt for this and it results in less tax, then you would obtain a refund of some of the tax paid at source. 

With regard to social charges paid already on investment income, there are other boxes in section 2 which should indicate amounts of income that have already been subject to these.

They will also probably have been pre-filled from information given to the tax office by your bank.