My wife and I have just been doing our 2017-2018 UK tax self-assessments online (yes I know... leaving it to the last minute... they are all done now though).

As during that tax year my income was below the personal allowance while she was in the basic rate range, I wanted to take advantage of the "Marriage Allowance" option of transferring some (£1,190) of my "unused" personal allowance to her.

While I was going through the self-assessment process, it did actually give me the option of doing this (I forget the exact details, but I do remember it asked for my wife's national insurance number). However while going through my wife's self-assessment (which we did second) there seemed to be no point at which she could mention such a transfer had taken place or was being claimed and there was no sign the transferred personal allowance had affected her tax calculation.

How is this actually supposed to work? I can imagine it might take a while for the transfer to register in HMRC's systems... but then would she just find herself credited with any overpaid tax, or will something need amending/resubmitting once her personal allowance has actually updated? Or did we miss some point where she should have claimed it?

  • This is a great question and I agree it's not clear from the online documentation about the Marriage Allowance. I think in your shoes I'd phone HMRC and ask them - they are usually very helpful with things like this.
    – Vicky
    Jan 22, 2019 at 22:15

1 Answer 1


The short story is "it just works".

Here's a longer account of what happened:

After submitting her tax return online, my wife left it a few days before logging in again to pay the amount owed. And found it was £200 or so (I forget the exact number) less than expected from the original calculation done with the submission. The saved calculation hadn't changed (but that's unsurprising; it is saved rather than dynamically updated). Unfortunately the online site doesn't let you see any more detail than how much it thinks you owe so we weren't completely sure what had reduced it. We didn't want to open a can of worms by resubmitting an unmodified self assessment just to see if the calculation updated, because we knew we'd get a letter through from HMRC in a little while anway...

Today that letter ("Self Assessment: Tax Calculation") showed up and does indeed show the effect of "Marriage Allowance Transfer" of £1150 of personal allowance reducing the bill by £230. There's also an explicit statement under a "We have the following comments on your tax return" heading that "Marriage Allowance has been transferred in line with your application".

Well done HMRC.

  • 3
    A good result by the standards of government IT perhaps :-) Jan 31, 2019 at 14:55
  • @GaneshSittampalam I've only used the online self-assessment forms once, a few years ago, but I was pleasantly surprised at the implementation.
    – TripeHound
    Jan 31, 2019 at 15:34
  • 2
    I think online self-assessment is ok in general. But the particular process described here doesn't sound great, even if it could have been much worse. Jan 31, 2019 at 16:39
  • 1
    It does slowly get better I think. This year's big change (that I noticed anyway) seems to have been cosmetic, adopting the .gov.uk stylesheet. Incorporation of some NI things some (many?) years ago seemed a significant milestone. Still, a lot of the time (e.g this case, and some other HMRC systems I've had to deal with) you're left with the impression it probably all makes perfect sense to "in the know" insiders who deal with this stuff every day, but there's not very much guidance to help novice users needing to get to grips with some new aspect for the first time.
    – timday
    Feb 1, 2019 at 10:00

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .