The Welsh Revenue Authority's payment guidance, updated on 11 November, confirms an interest-rate increase effective 11 November 2026. For overdue Land Transaction Tax (LTT), the annual rate is now 6.5%. Buyers completing a move in Wales should check that the tax return and payment arrangements are both in place.

How the interest rate is worked out

The 6.5% figure is calculated from the WRA's published formula: Bank Rate plus 2.5 percentage points. Bank Rate rose to 4% on 5 November, so 4% + 2.5% = 6.5%. The WRA charges simple interest on unpaid tax, rather than interest on previously accrued interest. WRA interest guidance · Bank of England decision

This is a charge for paying tax late. It does not change the LTT bands used to calculate tax on a Welsh property purchase. England and Northern Ireland's HMRC stamp-duty interest arrangements are separate.

Keep the filing and payment deadline visible

The official LTT overview says the return and tax payment are due within 30 days of the day after completion, or another effective transaction date. A return can still be required where no tax is payable. Ask your conveyancer to confirm the date that applies to your purchase.

Before the move, check:

  • Who will submit the return and arrange payment, and when you need to transfer funds to them.
  • Whether the tax money is included in your completion statement, so you keep it separate from removal and arrival costs.
  • Which payment reference will be used. The WRA's payment guide requires the 12-digit transaction reference for an online return; paper returns have different instructions.
  • When funds will reach the WRA. Its guide says BACS payments must be sent four working days before the due date.

Keep confirmation of filing and payment with your completion documents. Filing alone does not settle the bill. Separate late-filing or payment penalties may also apply; interest is not the only possible consequence of missing a deadline.

Use the property purchase tax calculator, selecting Wales, for a supported purchase estimate. Confirm the actual liability with your conveyancer, then record it and its due date in your moving budget. The calculator estimates purchase tax; it does not calculate overdue interest or penalties.