Provisional and estimated figures on a tax return

You can file a Self Assessment return containing provisional figures when a final number genuinely cannot be obtained before the filing deadline, provided it is a reasonable estimate and you say on the return that it is provisional. Put an X in box 20 and use box 19, “Any other information”, to explain why and when the final figure will follow. You must then give HMRC the final figure without delay, normally by amending the return within 12 months of the filing deadline.

What is the difference between a provisional figure and an estimated figure?

HMRC’s Self Assessment Manual at SAM121190 draws a clear line:

A provisional figure is a placeholder supplied pending the final, accurate figure. You expect to replace it.
An estimated figure is one you want HMRC to accept as final because an accurate figure can never be produced, for example where records have been lost.

The distinction decides how you complete the return. HMRC’s SA150 notes for the 2026 return say to put an X in box 20 only if you have used provisional figures and intend to send final figures as soon as you can. If you have used estimated figures, leave box 20 blank but explain in the “Any other information” box why you used them.

Valuations sit between the two. The Self Assessment Legal Framework manual at SALF206 accepts that valuations involve judgement and that more than one figure may be sustainable. Enter the valuation and say how it was reached. If you treat it as final, it stands as final, subject to HMRC’s right to enquire and your right to amend.

When will HMRC accept a provisional figure?

Only when the final figure is not available despite your best efforts. SALF206 says a return containing a provisional figure should only be submitted once it is clear that a more accurate figure will not be available before the filing date. The Enquiry Manual at EM5175 adds that HMRC does not accept pressure of work or the complexity of someone’s affairs as reasons, because the filing period gives at least three months and normally about ten.

HMRC’s own examples include:

income from abroad where the foreign figures are not yet known;
income from a deceased person’s estate still in administration;
a partner’s share of profits where the partnership figures are not ready when the partner must file;
self employed profits under the tax year basis, where accounts ending after 5 April are not finalised in time.

The last case is now the commonest. Since basis period reform, a business whose accounting year does not end between 31 March and 5 April may have to apportion two sets of accounts. HMRC’s guidance on the change says that if the accounts for the second part of the tax year are not finalised, you must estimate the profit, provide provisional figures and amend the return when you know the correct figures. See basis period reform explained.

For accounts information, EM5175 says a single estimated profit figure is rarely acceptable. The main genuine case is a new business whose first accounting period ends within three months of the filing date or after it, so for the 31 January deadline, periods ending on or after 1 November. Where some accounts information is provisional, HMRC expects a provisional figure in every box that would normally be completed. SAM121190 puts it plainly: there should be no short cuts because the figures are only provisional.

How do you flag provisional or estimated figures on the return?

Put your best estimate in the normal box, so that it is included in the tax calculation.
Put an X in box 20 if any figure is provisional.
In box 19, identify each provisional or estimated figure, give the reason and, for provisional figures, the date you expect to provide the final figure.

The SA150 notes warn that figures entered in box 19 are not included in the tax calculation, so the estimate must also go in the correct box. The Self Assessment Claims Manual at SACM5010 lists the same obligations for claims: a reasonable estimate taking account of all the facts, clear identification, the reason, and when the final figure will be available.

The capital gains pages (SA108) have their own box 53 for computations that include estimates or valuations. The SA108 notes say you must explain where and why estimates were used and how they were worked out, and for a valuation give its date and a full description of the asset.

HMRC will not reject a return because the reason or expected date is missing. SACM5010 and EM5175 say the omission is instead a factor in deciding whether to open an enquiry.

When must the final figures be given?

As soon as they are available. SALF206 says the correct figure should be notified to HMRC without delay, together with any amended self assessment. HMRC’s guidance gives no fixed date beyond that, but timing has consequences:

GOV.UK says you can correct a return within 12 months of the Self Assessment deadline. For a 2025 to 2026 return due on 31 January 2027, that means by 31 January 2028.
EM5175 tells officers that if the final figure is promised after the enquiry window, they should open an enquiry before the window closes to protect HMRC’s position.
After the amendment window, a reduction can usually only be claimed through overpayment relief, and HMRC can collect an increase through a discovery assessment.

The mechanics are covered in amending a tax return.

What if the final figure turns out lower or higher?

If the final figure reduces the tax and you amend in time, the self assessment is simply corrected. If the window has closed, the Self Assessment Claims Manual at SACM12058 says HMRC may allow an overpayment relief claim where the final figures produce a net reduction, but the claim will be refused if you ought reasonably to have known the final figures when you filed or before the amendment window closed.

If the final figure increases the tax and you have not amended, SACM12058 confirms HMRC can make a discovery assessment under section 29 of the Taxes Management Act 1970.

Can HMRC charge a penalty for using provisional figures?

Yes. SALF206 and EM5175 describe three situations:

there was no good reason for a provisional figure because the final figure could have been obtained in time;
the provisional figure was not a reasonable estimate given the information available;
you delayed unreasonably in giving the final figure and the original estimate was too low. In that case a penalty can apply even though the original return was neither careless nor deliberate.

These fall under the inaccuracy penalty rules described in penalties for errors in tax returns. The protection works the other way too: SAM121190 says returns with provisional figures should be accepted as long as they satisfy the filing requirement, so a properly completed return filed on time avoids a late filing penalty.

How does this work for a sole trader with a 31 December year end?

Illustration only. Priya’s accounts run to 31 December. Her 2025 to 2026 return must cover 6 April 2025 to 5 April 2026, so she needs nine months of the year to 31 December 2025 and three months of the year to 31 December 2026. Using the months method in HMRC’s guidance:

Accounts	Profit	Months used	Taxable
Year to 31 December 2025 (final)	£40,000	9 of 12	£30,000
Year to 31 December 2026 (management accounts)	£48,000	3 of 12	£12,000
Provisional total			£42,000

Her accounts to 31 December 2026 will not be ready by 31 January 2027, so she files on time with £42,000, an X in box 20 and a note in box 19 explaining that the January to April 2026 element is based on management accounts and that final accounts are expected by 30 June 2027. The final profit is £52,000, so that element becomes £13,000 and her taxable profit £43,000. She amends the return and pays the extra tax well before 31 January 2028.

What mistakes should you avoid?

Using provisional figures because the return was left too late; HMRC does not accept pressure of work.
Putting an X in box 20 for a figure you never intend to replace. That is an estimate and belongs in box 19 only.
Writing the figure only in box 19, so it is left out of the calculation.
Giving one profit figure instead of completing every accounts box.
Forgetting to amend when the final figure arrives, which can turn an innocent estimate into a penalty.
Agents using provisional figures routinely. SAM121190 tells officers to alert a compliance manager where an agent files a significant proportion of returns with provisional or estimated figures.

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Reviewed by Christine Anderson, Broker, Solar Protect. Last reviewed 8 October 2026. Part of Accountapedia, the Solar Protect guide to UK tax and accounting. This page is general information, not personalised advice.