Guya is 100% correct. This is a bit of a shock for some folks. You can deduct a huge list of items beginning with stamp duty and legal costs at the date of purchase, improvements throughout the life of the house, and costs of sale such as advertising and sprucing up. For every item, you must multiply the ££ cost by the exchange rate on the day of each expense (which you can find at
www.oanda.com).
If you return to the UK before selling and live in it in the UK for 2 years, you can deduct $500,000 of the gain (though all of the depreciation addback would still be taxable at 25%). It's $250,000 if only one of you live in it for the 2 years.
If you had received comprehensive tax advice before you acquired your greencard, your tax advisor would have warned you of this and advised that you consider selling the house before your greencards were activated. You would have then paid zero tax in the US (and zero tax in the UK as it was presumably your primary residence at the time).
Alternatively, you can keep the house and never sell it, letting it out into perpetuity.
If you email me separately. I will send you a copy of an article that I wrote for a magazine which contains a comprehensive list for deductions for a house sale.
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