SDLT Calculator.

When do I pay stamp duty?

You have 14 days from completion to pay SDLT and file the SDLT1 return. In practice almost every conveyancer handles both on the day of completion using funds you have already transferred.

Last reviewed 16 May 2026.

The statutory deadline

Stamp Duty Land Tax must be paid, and the SDLT1 return filed, within 14 days of the "effective date" of the transaction, almost always the completion date. Before 1 March 2019 the deadline was 30 days; it was tightened to 14 days for transactions completing on or after that date.

Why it normally happens on completion day

Conveyancers take SDLT from completion funds you transfer in advance, then pay HMRC and file the SDLT1 on the day of completion itself. There is no separate bill for you to deal with. The practical sequence on completion day:

  1. your mortgage advance and your own funds arrive in the conveyancer's client account
  2. completion happens between the two conveyancers (purchase price transfers to the seller)
  3. the conveyancer files the SDLT1 online and pays HMRC the SDLT amount
  4. the conveyancer applies to the Land Registry to update the title (using the SDLT5 certificate as proof of payment)

You will not see the SDLT line item in isolation, it is one entry on the completion statement your conveyancer sends in advance, along with their fees, search costs, and Land Registry fees.

What if I'm filing my own SDLT1?

Most buyers don't, but it is possible. You can register on the gov.uk SDLT online service and file directly. The deadline is still 14 days. If you choose this route you also need to obtain an SDLT5 certificate from HMRC before the Land Registry will register your title.

Late filing and penalties

Late filing carries automatic penalties: £100 if filed within three months of the deadline, £200 if later, and a tax-geared penalty (5%, 10%, or higher) if the return is more than 12 months late. Interest also accrues on unpaid SDLT from the original deadline.

Exchange versus completion

SDLT is triggered by the "effective date" of the transaction, which is completion, not exchange. You can exchange contracts months before completion without any SDLT consequence. Substantial performance before completion (taking possession, paying most of the price) can bring the effective date forward, but this is rare in a normal sale.

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