The Government brought in the ability for married persons to be able to transfer their tax free personal allowances between spouses. This means that one party can transfer up to £1,185 (2018-19) of their tax free earnings to their married partner, their Partner will then pay less tax as this amount will be at 0%.
You can apply to have the Marriage Allowance transferred going back to the 2015-16 tax year. This means that you could receive a tax refund as much as £662.
There are criteria you need to meet and the person transferring their personal allowance needs to be the one who applies.