When Is Stamp Duty Due?

Here's what actually starts the 14-day clock, and what it really costs if you miss it.

Completion vs exchange of contracts

This is the mix-up that trips up more buyers than anything else on this page. Exchange of contracts is the point where the purchase becomes legally binding: both sides sign, a deposit is paid, and neither party can pull out without financial consequences. But you don't own the property yet. Completion is a separate, later date, sometimes the same week, sometimes weeks later, when the remaining money actually moves, the keys are handed over, and legal ownership transfers to you.

Your stamp duty deadline runs from completion, which HMRC calls the "effective date" of the transaction, almost always the completion date for a standard residential purchase¹. Exchange doesn't start the clock. If you exchanged in April but didn't complete until June, your 14 days start in June.

A typical timeline: you exchange contracts on a Monday, agreeing a completion date three weeks later. Nothing about the stamp duty deadline moves during those three weeks. The 14-day countdown only starts on the actual completion day, when you become the legal owner. If completion falls on 22 July, your solicitor has until 5 August to file the return and pay the tax, regardless of when contracts were exchanged.

The 14-day deadline

You must file your SDLT return and pay the tax due within 14 days of the completion date¹. That's 14 calendar days, not working days, so weekends and bank holidays count. For our full explanation of who calculates and sends the payment, see how to pay stamp duty, and for how the amount itself is worked out, see our stamp duty rates guide.

What your solicitor actually does in the 14-day window

In most purchases the deadline is invisible to you because your solicitor is managing it. In the run-up to and immediately after completion, they typically:

• Before completion: prepare the SDLT return in draft using the agreed purchase price and your buyer status, so it's ready to submit as soon as completion happens
• Completion day: receive the funds transfer, release the money to the seller's solicitor, and confirm the deal has legally completed
• Day 1-3: file the SDLT1 return online through HMRC's portal and pay the tax from the funds they've been holding on your behalf
• Day 15-25 (approximately): receive the SDLT5 certificate from HMRC and forward it to the Land Registry with your registration application

Most solicitors don't wait until day 14 to file; they file within the first few working days so there's a buffer if HMRC queries anything on the return.

What if completion is delayed?

Property chains fall over, mortgage offers expire, and completion dates slip all the time. None of that changes the underlying rule: the 14-day clock only starts once completion actually happens, on whatever the new, delayed date turns out to be. A completion pushed back from a Tuesday to the following Monday just moves your deadline back by the same six days, no penalty, no need to notify HMRC in advance.

The risk sits at the other end. If your solicitor prepared the SDLT return assuming an earlier completion date and the date then changes, make sure they update the effective date before submitting. A return filed against the wrong completion date can cause processing problems with HMRC even when the tax figure itself is correct, and it's the kind of thing that's easy to miss when a chain has been rearranged at short notice.

Late payment penalties: worked examples

Say completion happens on 1 March. Day 14, and your legal deadline, falls on 15 March².

Paying 20 days late means the return is filed and paid on 4 April, 20 days after the 15 March deadline. That's comfortably within the "up to 3 months late" window, so you'd face a fixed £100 penalty, plus daily interest charged on the unpaid SDLT for those 20 days². On a typical tax bill, the interest itself is usually a modest add-on next to the flat penalty.

Paying 100 days late means the return is filed and paid roughly mid-June, past the 3-month mark. The fixed penalty rises to £200 instead of £100, and interest has now been accruing daily for over three months, so the total cost is meaningfully higher than the 20-day scenario, even though the underlying tax owed hasn't changed².

If a return still isn't filed 12 months after the deadline, HMRC can add a tax-geared penalty on top of the £200 fixed penalty, worth up to 100% of the SDLT actually due, in the most serious cases². In practice this level of escalation is rare and usually involves a return that's been ignored entirely rather than one that's simply a few weeks or months late. Either way, interest keeps accruing daily throughout, and a debt left unpaid for long enough moves into HMRC's standard debt-recovery process: reminders first, then formal collection action.

Scotland and Wales have longer deadlines

The 14-day rule above is specific to SDLT in England and Northern Ireland. Scotland's LBTT and Wales's LTT both give buyers 30 days from completion instead, more than double England's window. The underlying principle is identical (the clock starts on completion, not exchange, and your solicitor normally files and pays on your behalf), just with more room before the deadline bites. See our Scotland stamp duty guide and Wales stamp duty guide for the full rate detail in each nation.

If you genuinely can't pay on time

HMRC doesn't run a standard Time to Pay scheme for stamp duty the way it sometimes offers for other taxes; deferred or partial SDLT payments aren't generally accepted outside specific cases involving uncertain future consideration⁴. That said, HMRC has said it takes a supportive approach to buyers who get in touch about a genuine payment problem, looking at why the payment is missing and what can be done. If you can see a delay coming, whether that's a mortgage advance running late or a chain problem holding up funds, contact HMRC's Stamp Taxes helpline before the 14 days are up rather than waiting for a penalty notice. Being proactive doesn't guarantee a better outcome, but staying silent guarantees a worse one.

Does the 14-day clock start on exchange or completion?

Completion, not exchange. Exchange of contracts makes the sale legally binding, but you don't own the property and no tax is due until completion happens and ownership actually transfers. The gap between exchange and completion, anywhere from a few days to several months, doesn't count against your 14 days at all.

What if my solicitor misses the deadline?

The penalty and interest still land on you, the buyer, even though your solicitor did the filing. If a return is filed late because of a genuine delay on your solicitor's part, you can ask them to cover any penalty as a matter of professional negligence; most conveyancing firms carry indemnity insurance for exactly this kind of error. HMRC itself doesn't care whose fault the delay was. Its penalty and interest rules apply to the transaction, not to whoever happened to be responsible for missing the date.

14 days

Deadline to file and pay, from the completion date

£100

Fixed penalty for filing up to 3 months late

£200

Fixed penalty for filing more than 3 months late

100%

Maximum tax-geared penalty if still unfiled after 12 months

Last reviewed: 2026-07-03. Rates verified against gov.uk.