Maternity leave - how can I have underpaid tax?

[bananadramaclub]

I went on maternity leave in July 2023, so in the last tax year I had 3 and a bit months of normal pay (at 40% tax) followed by statutory maternity pay for the remainder of the year. I received a tax rebate for the first few months of the statutory pay.

I've just had my tax calculation through from HMRC and been told I owe around £350. I will have a good look at the breakdown but just in general terms I'm surprised it's possible to owe money in this situation? Once my pay went down it stayed down; I didn't take any KIT days, for instance. So presumably they underestimated my earnings at some point, but how?

It could be unrelated to the Mat Pay, I often owe because my work are useless and don’t tax my private healthcare benefit.

Because SMP is taxable. They’ll have reimbursed you some/all of your tax you paid in April May and June of 2023 because you then earnt nothing from employment for the rest of the year. You probs received your SMP without tax deducted.

or do you get any taxable benefits? Car? Private medical etc?

Thanks, both. No taxable benefits. I was expecting to be taxed on SMP but during the year rather than afterwards. Do they wait until afterwards so they know what rate to apply? (Sorry, stupid question!) I just thought they'd assume that I was on SMP for the remainder of the year and so apply the 20% rate.

Could it be interest on savings?

What was your tax code?