"Re: If you sell your house to your mom for $250K who then sells her house for $500K which has a basis of $50K does she have to pay tax on capital gains?Does the order matter?"

Are we talkng about 2 different houses in this scenario?

If mom sells her house for 500K and her basis is only 50K, if she qualifies for the 250k exclusion, she will pay capital gains on 200k in profit.

You selling your house to her, assuming you qualify for the 250K exclusion, you wouldnt have any capital gains to pay on your sale.