And you only need your national insurance numbers and your bank account details to claim.
The Marriage Allowance is available to married people who earn under Â£11,000 with a spouse earning under Â£43,000 before tax.
This applies to many part-time workers.
The allowance lets you transfer Â£220 of their tax free allowance to you - meaning they pay Â£220 less in tax over the course of the year.
And you can backdate your claim to the tax year that ended in April - meaning the Government will send those eligible a cheque for Â£220.
It’s very easy to claim online in under five minutes. There are no long forms to fill out. The only details you need are both of your national insurance numbers and the last four digits of your bank account.
It doesn’t affect any other benefits.
You can claim online here