Tax calendar.

For individuals, 31 January — the filing deadline, the balancing payment and the first payment on account all fall on it — and 31 July for the second payment on account. For companies, corporation tax nine months and a day after the year end, and the accounts filing deadline, which is a different date. For employers, every payday, because payroll has to be reported on or before it.

A fixed penalty applies immediately at midnight, with no discretion for being a day late and regardless of whether any tax is owed. It escalates at three, six and twelve months, and interest runs on unpaid tax separately from the penalties. Filing on time with an estimated figure and correcting it later usually costs less than filing late.

No. The obligation to file and the obligation to pay are separate, and the penalty for late filing applies even when the return shows nothing owed. It is one of the most common and most avoidable charges we see.

Often not, and assuming they are is a reliable way to pay interest. Company accounts and corporation tax have different deadlines from each other. VAT filing and payment usually share a date, but payment must clear rather than be initiated by it.