Let Property Campaign calculator

How is the estimate worked out?

1. Which years. From when you started letting, as above. The current year stays out, and last year goes on a tax return until its 31 January deadline: Include the income you had in the year before the current tax year on a tax return rather than in your disclosure.
2. The tax for each year. Your profit is added to your other income and taxed on that year’s rates and allowances, with mortgage interest treated the way it was that year. Losses carry forward.
3. Interest on each year’s tax, to the day you pay.
4. The penalty range for each year, from your answers about HMRC and what you knew.

No records for the early years? Use your best estimate and keep your workings. What to do without records

How is interest calculated on late tax payments?

Daily, simple interest, from the date the tax was due to the day you pay. This means that an amount that is due and payable on 31 January 2023 (late payment interest start date) and paid on 1 February 2023 (late payment interest end date) attracts 1 day of late payment interest. If you never sent a return, it starts when the tax would have been due had you sent one on time. HMRC’s manual says the late payment interest start date for the tax charged by the amendment or assessment is the date on which tax would have been due and payable if the original assessment had been complete and accurate, and made at the correct time.

Each year’s tax was due on 31 January after the tax year ends. From the second year on, we also count payments on account, due on 31 January in the tax year and 31 July after it, the way HMRC’s own calculator does. HMRC’s manual on assessments it raises for several years in a row says that for each year after the first, interest runs from The due dates of the payments on account, and the balancing payment for the year of assessment. Its legal manual reads the law more narrowly: They will not be required to make payments on account if they do not file a tax return for the preceding year. So the calculator shows both figures.

The rate is the Bank of England base rate plus 4% (plus 2.5% before 6 April 2025). When we checked on 31 October 2026 it was 7.75%, from 9 January 2026. Each period uses the rate in force then:

From HMRC’s table of interest rates. Days in a leap year count as one 366th of a year, as in HMRC’s calculators.

How is the penalty range worked out?

As a percentage of each year’s tax, never of the interest. The potential lost revenue (PLR) from a failure to notify chargeability for income tax (IT) or capital gains tax (CGT) is the amount of tax that is unpaid on 31 January next following the tax year. The calculator picks the row below from your answers: whether HMRC wrote to you first, what you knew, and when you tell HMRC.

If it was not deliberate, the “within 12 months” rows apply when you tell HMRC within 12 months. HMRC’s manual counts those months from the day after the tax was due, so for each year that means by the next 31 January. HMRC decides how to class what you did, and does not start by assuming it was not deliberate: Whilst upon the facts a first failure could perhaps be non-deliberate this should not be the default position and you should always consider whether it was deliberate behaviour. For a deliberate failure told more than 3 years after it happened, the lowest rate is normally 10 points higher. That does not apply if it was not deliberate. The penalties in full

How was mortgage interest treated in earlier years?

Up to 2016 to 2017 it was an ordinary cost. Then the part you could take off the rent fell each year, and the rest became a 20% credit:

• 2017 to 2018: 75% off the rent, 25% as a credit
• 2018 to 2019: 50% off the rent, 50% as a credit
• 2019 to 2020: 25% off the rent, 75% as a credit
• 2020 to 2021 onwards: 0% off the rent, 100% as a credit

Furnished lets could also take off 10% of the rent, less any bills a tenant would normally pay that you paid, up to 2015 to 2016, and the £1,000 property allowance only started in 2017 to 2018. The calculator applies each year’s own rules.

Can I use HMRC’s own calculator?

Yes, on a computer with Adobe Reader. This form is interactive (one that you complete on screen) and you must use Adobe Reader to complete it. There are two: a tax, interest and penalty calculator for the tax years ending 5 April 2010 to 5 April 2024 and an interest and penalty calculator for the tax years ending 5 April 2006 to 5 April 2024. Neither covers 2024 to 2025, which this one does, and this one works on a phone.

Is there a reasonable excuse?

Only if it was not deliberate, you had a reasonable excuse such as serious illness, and you told HMRC without unreasonable delay once it ended. Not knowing the rule is rarely enough on its own. Reasonable excuse explained

How much rental income can I have without paying tax?

From 2017 to 2018, up to £1,000 of rent a year is covered by the property allowance. A room in your own home can use Rent a Room, with a limit of £4,250 up to 2015 to 2016 and £7,500 since. Above that, profit is taxed once your income passes your Personal Allowance. Tax on rental income

What does the estimate leave out?

• Companies, trusts and partnerships, property abroad, and living abroad.
• Capital Gains Tax on selling a property, and any other income you never declared.
• Penalties for returns you were asked for and did not send, or sent with the rent left off.
• Joint owners: each works out their own share, and each makes their own disclosure.

What if I cannot pay?

Talk to HMRC before you send the disclosure. If you cannot pay the full amount, you’ll need to let HMRC know as soon as possible and before you send in your disclosure. You have 90 days from HMRC’s acknowledgement to send it and pay.

What is the Let Property Campaign?

The Let Property Campaign is for landlords who owe tax through letting out residential property in the UK or abroad. You tell HMRC first, then work out and pay what you owe. The Let Property Campaign, step by step

Other questions about the Let Property Campaign calculator