Thanks for that. The issue I have is that as the company is based in Dubai they don't pay vat and if I wack 19.6% on to of my invoice they will stop using me. Nor can I afford to absorbe the cost by reducing my earnings by 19.5%. Does anyone know a way around this?If you're resident in France (basically, if you're physically present in France for at least 183 days in a calendar year), then you're most likely "tax resident" in France. You probably should set up some form of business entity to handle your consulting business - the precise form depends on what line of work you're in and what your expected revenues will be in a year.
If you're under the service threshold (about € 32K a year), then you can set yourself up as an AE (auto entrepreneur) and you'll pay a flat percentage for French cotisations (social insurances). Your income tax will be figured based on a percentage of your take, with no deductions for expenses. The big advantage of the AE is that you're not subject to VAT (at 19.6%) but you also can't deduct the VAT you pay for your costs.
With just about any other sort of business entity, you register for the VAT - and thus will have to charge 19.6% VAT on your billings for your services carried out while you are physically present in France. You'll have to produce financial statements, but that means you get to deduct your business expenses and you can deduct VAT paid from the VAT you charge your clients.