Updating post from Reddit.
Hello we have a house jointly me and my partner. which has no mortgage. We are planning to put it on rent. I am higher rate tax payer but my wife is lower rate tax payer. So the rent generated from this house can I show the complete rent has her income instead of mine to save tax ?
Default position is the income will be shared 50/50 and you'll both pay tax on your half at your marginal rate.
If you want to do something different, then you'll need to sign a deed of assignment, giving them full beneficial interest in the property. They will need to take full responsibility for the letting, but then they can claim all the rental income as their own and not yours.