If you filed a self assessment return with tax due for 2024/25, HMRC will expect a second payment on account by 31 July. It's easy to lose track of, because nothing new has happened since January: no fresh invoice, no reminder letter for most people — just a standing instalment quietly coming due again.
Payments on account apply if your last tax bill was over £1,000 and less than 80% of it was collected at source. That description fits most self-employed dentists precisely: associates paid gross by the practice, locums working across several sites, and sole-trader practice owners all fall squarely inside it. Two employed dentists on PAYE, by contrast, rarely see a payment on account at all — so if you've moved from employed to self-employed, or incorporated then unwound it, this can be the first year the July payment applies to you, and it arrives without warning.
Each payment on account is normally half of last year's tax bill, on the assumption this year looks similar. If your income has genuinely dropped — parental leave, a career break, reduced sessions — you can apply to reduce the payment via your HMRC account or form SA303. But reduce it too far and HMRC charges interest on the shortfall from the original due date, currently running at 7.75%. We see this cut both ways: associates who had a strong year assume the reduction is safe because "things felt quieter," and end up paying interest on top of the balance the following January. Any reduction should be based on an actual forecast of the year, not a feeling.
For associates over the £50,000 threshold, July is also quarter-two of Making Tax Digital reporting — see our note on the first quarterly deadline. The two obligations are separate (one is a payment, one is a report) but they land in the same fortnight, which is exactly when disorganised records cost the most time. If your bookkeeping is current, both are a non-event; if it isn't, this July is a rough month to find out.
We calculate and confirm both payments on account for every self-employed client as part of the fixed fee, well ahead of each deadline — so 31 July is a number you already knew about, not a surprise.
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