I don't have all the answers for you, but let me try to give you what I know:
I am getting a little lost as to how foreign dividends are treated in France as well, especially as there is something about a new 3% tax???? Although not sure relevant for last years tax form or whether even gone through parliament yet.
I think this is still in the proposal stage - but not sure of that.
If you receive dividends in the UK, there is already 10% tax credit taken into account.
If for example I received 20,000 pounds in dividends in the UK, there is 2,222 pounds already taken in tax.
Take a look at the French tax form 2047. There is a chart on p. 3 of the form showing "Crédit d'impôt : taux applicables aux revenues nets de l'impôt prélevé à la source" For the UK, dividends are indicated as having a taux of 11.2% (which is, I believe what the fisc is assuming you have been assessed for - but read through the instructions for that form to be sure).
Do I then get a 40% abatement here, is that on the gross amount?
There is then an allowance - if I live with my partner in France is this taken as being the household allowance or single allowance if not married?
I don't believe you get an abatement on dividends - but you do get a credit for taxes already paid in the UK. (Again, I've never had to deal with dividends, so check that out.) If you aren't married or PACS'd with your partner, then you each have to fill out a separate tax declaration.
So would it be 22,222 less 40% less allowance and then this amount added to any other income and taxed at marginal rates? And is the tax already paid at source in the Uk then taken into account?
There is also mention in some threads of a further 11.5% credit?
Foreign source income is handled a little differently than regular income. Normally, it's added into the total, but you are allowed a credit, either in the amount of the taxes you have already paid or a credit that is equal to the French tax on that income. Perhaps someone more familiar with taxation of foreign dividends can help us here.
And what are social charges taxed at? 12.3% on gross amount?
What if already paying into French system (RSI payments etc) each year?
Not sure on that one, but if you're assessed social charges on your dividends, it's a separate charge over and above any RSI payments you make on your French income.
OK, who here declares foreign dividends and can help out on this question?
Cheers,
Bev