Hi. My name is*****'m looking at your question now and will post my answer or ask for more information here in a short while.
Gains made by non-UK residents on UK residential property became taxable in the UK from 6 April 2015 as you can read here and here. There are three ways you can work out the gain but as you have owned your property for 17 years, the most beneficial way will almost certainly be to use the 5 April 2015 value of the property as your "cost" for CGT purposes instead of the original purchase price. The first £11,100 of gains made in the current tax year will be tax free. CGT on residential property gains is charged at 18%, 28% or a combination of the two rates depending on the level of your UK income in the tax year the gain is made.
I'm not an expert on French tax but I strongly suspect that the gain will be taxable in France and if it is, then you will get credit for any UK CGT paid against the tax you pay in France. Clearly, the gain will be worked out in a different way for French tax purposes compared to the way used for UK tax purposes. Any disposal must be reported to HMRC in the UK within 30 days of the sale.
I hope this helps but let me know if you have any further questions.
I cannot see how you arrive at a CGT liability of £132,000. If you use the 5 April 2015 value as your "cost" instead of £185,000 and you sell the property now for £X, what is your gain? In my answer, I said that you have the option to "use the 5 April 2015 value of the property as your "cost" for CGT purposes instead of the original purchase price." I can only think you have used the original purchase price as your "cost".
If you use the 5 April 2015 value as your cost, you deduct that from the disposal proceeds to arrive at your gain. The first £11,100 of the gain will be tax free. Assuming you have no UK income, the first £32,000 of the net taxable gain if there is one will be charged to CGT at 18% and any balance will be charged to CGT at 28%. This is assuming a disposal in the current tax year, 2016/17.
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