The Lemon Fool

... Working/living in France as a consultant (single source) to an International Company with a branch in Paris.

Paid (thru a UK Agent who invoices the French Company) by invoice to a UK Agency.

Currently paying income tax in France, but have been advised I may also be liable for "Social Charges" (which amount to the best part of another 50% of earnings), which definitely would make my current position un-economic.

Any advice on how to best deal/minimise the impact of the the liability of these charges (except - move out of France) appreciated.

Thanks in advance

There is an exemption for a maximum of two years when on secondment from one member state to another. A pal of mine did this years ago - basically you pay income tax where you reside (France in your case) and NI in the UK, which used to be beneficial. I don't know if you can then 'switch' employer to be on secondment again for another two years. My experience in France was that generally the various bits of the state don't communicate very well, but you could be chancing your arm.

OP should get professional advice.
What I can say (10-11 year tax resident in France) is that:
- tax & social charges now a well joined up system (was not the case a decade ago);
- all professional activities in France are subject to social charges (+health etc.)
- professional income received from uk or elsewhere is also subject to social charges (albeit often a good deal less).