If you have less than £1,250 of unused personal allowance to spare, you may still be able to transfer this to your higher-earning partner. However, this can become slightly more complicated than transferring the typical £1,250. This amount has been established as any less could compromise any advantage the marriage tax allowance could provide.
For example, if less than £1,250 is transferred to a higher-earning partner, the non-taxpayer runs a risk of exceeding their shortened personal allowance and if gone over, they could end up paying tax on the amount they have gone over.
Therefore, while you can transfer less than the standard amount of personal allowance for marriage tax allowance, it’s important to make sure it will still provide an advantage to you.