Paying stamp duty: SDLT returns, deadlines and penalties

The buyer is responsible for stamp duty, but in most purchases the conveyancer or solicitor files the SDLT return online and pays the tax from funds the buyer provides before completion. Buyers can file their own return, using HMRC's online service or a paper form, but most leave it to the conveyancer.

Even when a professional files the return, the buyer signs a declaration that the information is correct and stays liable for any mistakes. Checking the price, dates and any reliefs claimed before the return is sent is worthwhile.

The SDLT return must reach HMRC, and the tax must be paid, within 14 days of the effective date of the transaction, which is usually completion (GOV.UK, accessed 20 Oct 2026). The deadline applies even when no tax is due but a return is still required.

A return is needed for most purchases of residential property costing £40,000 or more (GOV.UK, accessed 20 Oct 2026). The conveyancer receives a certificate, the SDLT5, once the return is accepted, and the Land Registry needs it to register the new owner.

Stamp duty is paid to HMRC by bank transfer, online banking or debit card, using the unique transaction reference number from the SDLT return as the payment reference. Most conveyancers collect the tax with the deposit and other completion funds, then pay it on completion day.

Payment must clear by the deadline. A payment that arrives late, even by a day, can attract interest.

A late SDLT return incurs an automatic penalty of £100, rising to £200 if it is more than three months late (GOV.UK, accessed 20 Oct 2026). Returns filed more than 12 months late can face a further penalty of up to the amount of tax due. Interest is charged on tax paid late.

HMRC can cancel a penalty where there is a reasonable excuse, such as a serious illness. An appeal is made in writing within the time shown on the penalty notice.

An SDLT return can usually be amended within 12 months of the filing deadline (GOV.UK, accessed 20 Oct 2026). Amendments are used to correct mistakes, such as a wrong price or a missed relief, and can lead to a refund or to extra tax being due. The conveyancer who filed the return often handles the amendment.

After that period a refund needs a formal claim, and the time limits differ. The guide to stamp duty refunds explains when tax can be reclaimed and how.

Some transactions need more than one return. A lease with rent that is reviewed, an overage payment or a price that depends on future events can mean further returns and payments later. Linked purchases between the same buyer and seller are added together, which can change the rate charged on each part.

These cases are common in commercial transactions and in some new-build purchases. A conveyancer can confirm whether further returns may be needed.