I suspect you have some ancillary complicating issues if you're structuring a house sale that way.
As to the question of "should she pay tax?" - that's really a theoretical question because of what people should or shouldn't be obligated for on the tax issue. If you're asking "what would she have to pay, if anything", that's really a question for a CPA or tax attorney.
There isn't enough information provided for anyone to answer what level, if any, of taxation this transfer would invoke.
It is my (non professional) understanding that we delay paying the taxes due on the sale of a house by buying or building another house that is worth more than the one we sold. Eventually we make the last sale without a purchase and that's when we pay the piper, so to speak.
However, you are talking about selling in one name and purchasing in another. I don't think that will count. It might vary in other countries, and even in the US it could vary depending on how the gift is handled. Because that's what it is. A gift of the money to build a house. So it will probably be subject to gift taxes. It will be income for you.
I would very definitely consult a real estate attorney or CPA as previously advised. This is too complicated to guess or to play around with.
As to the question of "should she pay tax?" - that's really a theoretical question because of what people should or shouldn't be obligated for on the tax issue. If you're asking "what would she have to pay, if anything", that's really a question for a CPA or tax attorney.
There isn't enough information provided for anyone to answer what level, if any, of taxation this transfer would invoke.
However, you are talking about selling in one name and purchasing in another. I don't think that will count. It might vary in other countries, and even in the US it could vary depending on how the gift is handled. Because that's what it is. A gift of the money to build a house. So it will probably be subject to gift taxes. It will be income for you.
I would very definitely consult a real estate attorney or CPA as previously advised. This is too complicated to guess or to play around with.