Reacting to: Taxpayers urged to get ahead of July Self Assessment payment deadline (gov.uk / HMRC) →
HMRC put out a reminder this week that the second Payments on Account deadline for Self Assessment falls on 31 July — a bill equal to half of your previous year's total tax liability, due again just six months after the January payment. It applies to most people in Self Assessment, with a couple of exceptions: it doesn't apply if your last tax bill was under £1,000, or if you already paid more than 80% of what you owed through something other than Self Assessment, such as PAYE.
Why this one catches people out
The January deadline gets all the attention, for obvious reasons — it usually comes with the final balancing payment for the previous tax year on top of the first payment on account for the current one, so it's the bigger, more painful date in most people's calendar. July's payment is exactly half that size in most cases, which paradoxically makes it easier to forget about, or to assume it's smaller than it actually is. HMRC's own figures show nearly 2 million Self Assessment taxpayers have used the HMRC app since it launched, with over 110,000 payments made through it since April this year — a sign that more people are managing this deadline digitally rather than being caught out by a letter landing after the fact.
What actually happens if you miss it
Miss it, and HMRC starts charging interest on the outstanding amount from the day after the deadline, for every day it remains unpaid. It's not usually a dramatic cliff-edge the way some deadlines are, but it's an entirely avoidable cost — interest that simply didn't need to accrue if the payment had been planned for. HMRC's Chief Customer Officer, Myrtle Lloyd, put it plainly: “We know managing a Self Assessment tax bill isn't always straightforward and we are here to help,” pointing people toward payment plans — monthly or weekly — for anyone who can't pay the full amount in one go.
The bit that's easy to miss
What often trips people up isn't the deadline itself, it's not knowing the figure until the last minute. If your bookkeeping is current throughout the year, your payments on account are never a surprise — you already know roughly what's coming, because the year's income and expenses have been tracked as they happened rather than reconstructed under pressure the week before the deadline. That's exactly the gap our tax planning support is built to close for clients, and it's a big part of what we do for the sole traders we work with — keeping the numbers current enough that 31 July is just another date, not a scramble.