Avoiding capital gains on sale of home

Hi there, US citizen living in the UK, domiciled here, and own a property. My spouse is non-US.

There seems to be a $250K exemption on the capital gains from your primary residence (if I file alone, as spouse isn't US citizen).

In the UK there are no capital gains on the sale of your house.

I was thinking of giving the house to my spouse to avoid US capital gains, but then I saw there is US gift tax to be paid for gifts above ~$150K to a non-US spouse (while there is no gift tax in the UK for gifts to a spouse).

Is my understanding correct? And is the ~$150K exemption annual? If so, could I then gift a share of the house over several years to avoid US gift tax (if stay below ~$150K of market value, and if gifting a share of a property is even possible)? Any other advice on how to legally avoid paying US tax on the sale of a house (if gain exceeds $250K)?

This explains the U.S. gift tax in general, so unless the rules are different for transfers to non-USCs you could choose to have the amount in excess of the annual exclusion come out of your lifetime exemption (assuming you haven't used it up, which is unlikely unless you're wealthy as that amount is now over $10 million).

"While U.S. citizen couples can gift an unlimited amount between spouses without any estate or income tax consequences, an American with a non-citizen spouse is limited to a special annual gift tax exclusion of $149,000 (2017) for gifts to a non-citizen spouse"
https://thunfinancial.com/home/american-expat-financial-advice-research-articles/gifting-appreciated-assets-non-resident-spouses/ [nofollow]

Not sure if it means I need to pay tax above the exclusion or just requires filing a form?

"While U.S. citizen couples can gift an unlimited amount between spouses without any estate or income tax consequences, an American with a non-citizen spouse is limited to a special annual gift tax exclusion of $149,000 (2017) for gifts to a non-citizen spouse"
https://thunfinancial.com/home/american-expat-financial-advice-research-articles/gifting-appreciated-assets-non-resident-spouses/

Not sure if it means I need to pay tax above the exclusion or just requires filing a form?

It just means filing a form. I filed form 109? for tax year 2017 when gifting money to my son to help him buy a house. It was easy enough to do, the form takes you through  the steps and comes up with tax owed = 0.

So if I understand it correctly in order for me to avoid paying capital gains tax on the sale of the house (if gain >$250k) I could gift the house to my spouse, file the form, and then when my spouse sells the house she pays no capital gains tax as she's not a US citizen and UK doesn't tax this. I'll probably run this by a tax advisor. If this works it must be a common practice?

If there is a mortgage there may be stamp duty payable on the transaction.  The IRS might attempt to use the anticipatory assignment of income doctrine to ignore the transaction.