The short answer
A Let Property Campaign disclosure runs in two stages. You tell HMRC you intend to disclose. HMRC sends back a disclosure reference number, and from the date you receive that acknowledgement you have 90 days to work out the tax, the interest and the penalty, submit the whole thing and pay it.
The order is what protects the penalty range. Years of rent nobody declared, a boxfile of letting agent statements that stops in 2021, a tenancy agreement you can’t find: none of that stops you notifying HMRC this week. Waiting until every bank statement is in front of you does stop you, and nothing protects the unprompted penalty range while you wait.
Total Books says the same thing on every one of these calls. Notify, then work.
Total Books is a regulated, advisory-led practice. We check any planning against HMRC Spotlight guidance, and we only put forward positions we would sign our own name to.
This guide walks the sequence in the order it happens. Which route you should be using in the first place is a separate question, and our guide to choosing between HMRC’s disclosure routes settles it before you notify anything.
Key takeaways
- Notify first, gather second
- Two reference numbers, doing two different jobs
- Behaviour sets the years: four, six or twenty
- You propose your own penalty percentage
- Telling, helping and access move it within the range
- Interest runs daily and no reduction touches it
- The campaign carries no protection from prosecution
Free, and no obligation
Not sure whether to notify yet? Book a free 15 minute call and we’ll tell you what you’re looking at before you contact HMRC.
Phone 029 2002 6505.
The disclosure in order
Notify first, then the ninety days start
What HMRC expects at each stage, and roughly where in the window it belongs.
- 1Notify HMRCA short online notification that you intend to disclose. Nothing is calculated yet, and no figures are given.Before the clock starts
- 2Get your Disclosure Reference NumberHMRC issues the reference and the ninety day deadline in the same letter. Keep both.Day 1
- 3Rebuild each yearRent received, allowable costs and finance costs, year by year, with the evidence you can actually produce.Days 1 to 30
- 4Self assess the penaltyYou choose the behaviour band and the reduction you believe you have earned, and you justify it.Days 31 to 70
- 5Make the offer and payTax, interest and penalty go in as one offer. Payment is expected with it, or a time to pay arrangement is asked for.Days 71 to 90
Not yet notified? That is the right moment to talk, because everything after it runs on a fixed clock.
Talk it through before you notifyHow do I notify HMRC that I want to make a disclosure?
You notify HMRC of your intention to disclose before you send any figures at all. It’s a short step. You’re telling HMRC that you owe tax on letting income and that you’re going to put it right, not telling them how much.
You’ll need three things: your National Insurance number, your Unique Taxpayer Reference if you already have one, and a start date for the letting, even an approximate one. An old tenancy agreement or the first entry in a rent book will usually give you that date.
In our experience, landlords in this position have often never been inside Self Assessment at all. That isn’t a problem at the notification stage, and HMRC issues a UTR as part of bringing you into the system.
HMRC then sends a notification acknowledgement. Read the date on it. That date is the one everything else runs from.
The sequence, in the order it happens
Tell HMRC you intend to disclose. No figures, no computations, no paperwork attached.
HMRC replies with your disclosure reference number. The date on that letter is the date the clock starts from.
Profit for each year, then the interest, then the penalty percentage you propose from inside your own range.
Submit the disclosure with the formal offer, then pay using the payment reference number, inside the same 90 days.
Nothing in stage two starts the clock. Stage one does.
What is a disclosure reference number, and how is it different from the payment reference number?
The disclosure reference number identifies your case. The payment reference number gets your money to it.
We see the two mixed up regularly at Total Books, so it’s worth saying plainly. Quote the disclosure reference number on the disclosure and on any correspondence about the case. Quote the payment reference number when you pay, whether you pay online or at your bank.
Lost the reference numbers? The Let Property Campaign helpline will retrieve both against your details. Don’t start a second notification to get a fresh set, or you’ll end up with two open cases and a conversation about which one is real.
How long do I have to complete the disclosure?
You have 90 days from the date you receive the notification acknowledgement. Not from the date you first thought about it, and not from the date HMRC wrote to you about rental income.
Everything below has to fit inside those ninety days. Inside them you chase the letting agent for old statements, pull bank statements from a closed account, rebuild each year’s profit, calculate the interest, self assess the penalty, submit the disclosure and pay.
The window opens on the acknowledgement date, not on the day the worrying started.
Ninety days is not generous. It is workable. A landlord with three years of tidy agent statements will be finished inside a fortnight. A landlord with twelve years, three properties and two mortgages will use most of the window.
Missing records don’t stop you starting. HMRC expects reasonable estimates where paperwork has gone, provided you mark which figures are estimated and how you arrived at them. Bank statements, letting agent statements, mortgage interest certificates, deposit scheme records and old tenancy agreements between them rebuild most years.
Total Books rebuilds those years in Xero, with Dext lifting the figures off whatever paperwork survives, and you send documents through our secure client portal rather than by email. Our guide on submitting a disclosure with missing records sets out the methods that hold up.
How do I work out the rental profit for each year?
You rebuild the profit year by year, on the basis the property pages of a Self Assessment return would have used at the time. Gross rents received, less the expenses allowable in that year, gives the taxable profit.
Mortgage interest is not a deduction. Since 2020/21 finance costs give a basic rate tax reducer instead, which is why a landlord with a large mortgage can show a taxable profit while feeling like they made nothing. Our guide to reducing let property tax explains how the credit is applied.
The years are old, but you aren’t limited to declaring the rent and nothing else. Letting agent fees, repairs, insurance, ground rent, service charges and replacement of domestic items all reduce the figure you’re disclosing. A managing agent’s annual statement usually does the most work here, because it carries the gross rent, the commission and most of the deductions on one page.
Property losses carry forward against later profits, which is why a loss making year still goes in. Void periods, a tenant leaving mid year and a major repair between tenancies all belong in the computation rather than being rounded away.
The Total Books guide to rental profit calculation works it through from gross rent to taxable profit.
A worked example. A landlord moved in with her partner in 2018 and let her old two bedroom flat in Newport rather than sell it. She never reported the rent, believing the mortgage cancelled it out, and she was employed throughout, so the whole profit fell at the basic rate. Gross rents averaged £9,600 a year. Allowable expenses, including agent fees, insurance, a boiler repair and the annual gas certificate, averaged £2,900. Mortgage interest of £4,100 a year was not deductible and instead gave a basic rate credit against the liability. Taxable profit came out at roughly £6,700 a year rather than the £2,600 she had assumed. Rebuilding those expenses across the six years being disclosed took about £17,400 off the profit going into the disclosure.
How many years do I have to go back?
Four years, six years or twenty, and which one applies follows your behaviour rather than how long the property was let.
Behaviour sets the number of years
| Behaviour | Years to disclose |
|---|---|
| You took reasonable care and still paid too little | 4 years |
| You were careless | 6 years |
| The failure was deliberate | 20 years |
Reasonable care is the category most often written off too early. Where you took reasonable care and tax was still underpaid, there’s normally no penalty at all. You pay the tax and the interest, and that’s the end of it.
Careless covers most real cases: not knowing rental income was reportable, assuming a loss meant nothing to declare, or leaving it to a partner who never filed.
Deliberate means you knew and chose not to. Deliberate opens a twenty year window, and it’s the point at which a disclosure stops being a tidying exercise.
How do I work out the penalty I offer HMRC?
You propose your own penalty percentage, inside the statutory range for your behaviour, and HMRC either accepts it or comes back.
Never registered, so you failed to notify HMRC that you had income to declare? Schedule 41 Finance Act 2008 applies, and the ranges look like this.
Schedule 41 penalty ranges, failure to notify
| Behaviour | Unprompted | Prompted |
|---|---|---|
| Non deliberate, more than 12 months after the tax was due | 10 to 30% | 20 to 30% |
| Deliberate | 20 to 70% | 35 to 70% |
| Deliberate and concealed | 30 to 100% | 50 to 100% |
Where you were already filing returns and the figures were wrong, Schedule 24 Finance Act 2007 applies instead, with careless running from 0 to 30 per cent unprompted and 15 to 30 prompted, and the deliberate bands matching the table above.
Three things then decide where you land inside the range, and this is the part you can influence:
- Telling, worth up to 30 per cent
- Helping, worth up to 40 per cent
- Giving access to records, worth up to 30 per cent
Those reductions move the penalty within the range. They never reduce the tax and they never touch the interest.
One restriction is worth knowing about. Where the failure ran for a long time, normally more than three years, HMRC restricts how far the penalty can come down. A landlord disclosing twelve years doesn’t get the same floor as a landlord disclosing two, and we set expectations on that at the first call.
The Total Books case study on the site records a landlord who disclosed twelve years of undeclared rental income through the campaign and settled with the penalty loading cut to 10 per cent. That was his position on his facts. In the client’s own words, every step of the process was “clearly explained and they went over the calculations with me so that I could confirm that I was happy with the information before they submitted the details to the HMRC”.
★★★★★ Dean W. in his own words, Google review, May 2022 · Read the full Let Property Campaign case study
Is my disclosure unprompted or prompted?
Your disclosure is unprompted where you had no reason to believe HMRC had discovered, or was about to discover, the problem. That’s the statutory test, and it sets which floor applies.
A nudge letter usually ends it. Once HMRC has written to you about rental income, arguing you had no reason to think they were onto you becomes difficult, and on a non deliberate case more than twelve months old the minimum moves from 10 per cent to 20 per cent.
That ten point gap is the whole argument for acting before the post arrives. Our comparison of prompted and voluntary disclosure sets the two positions side by side.
A nudge letter isn’t a compliance check, though. HMRC has to open one of those separately to demand records.
Notify, then work
Let Property Campaign
Ninety days is enough time when somebody is running the order for you
Notification, the two reference numbers, the year by year rebuild, the penalty you propose and the payment, taken in sequence rather than all at once.
See how our Let Property Campaign service worksWhat happens after I submit, and how do I pay?
You submit the disclosure with a formal offer covering the tax, the interest and the penalty you’ve self assessed. HMRC then accepts it or queries it.
Acceptance creates a binding contract settlement, and HMRC writes to confirm it. Keep that letter, because it’s the evidence the years are closed.
Payment goes in using the payment reference number, inside the same 90 day window. Paying is part of the deadline, not something that follows it.
Where HMRC comes back with questions, that isn’t a rejection. Most queries concern a single year or a single expense, and they’re answered from the working papers you already built.
A second worked example. A landlord let a terraced house in Bristol for six years and took the rent in cash, so there was no paper trail beyond the tenants’ bank transfers for the last two years. He was employed throughout. Gross rents across the six years came to £51,000 and allowable expenses, reconstructed from bank statements and two years of agent statements, came to £16,400. That left £34,600 of taxable profit and about £6,920 of tax at the basic rate. Interest, running daily from each original due date, added roughly £2,310, because the earliest years had been outstanding the longest. The penalty was self assessed at 15 per cent of the tax, giving £1,038. The full offer came to about £10,268, and the penalty was the smallest of the three parts.
Interest outweighing the penalty is normal on older disclosures. Late payment interest has been set at base rate plus 4 per cent since April 2025, up from base rate plus 2.5 per cent. In the campaign’s 2025/26 figures, reported by AccountingWEB from HMRC data in July 2026, interest collected outstripped penalties by more than twelve to one.
What happens if I miss the 90 days or cannot pay in full?
If the window closes on you
Miss the 90 days and HMRC can treat the disclosure as abandoned and open a compliance check instead, and a case that starts as a check doesn’t carry the unprompted range at all.
Where the problem is payment rather than time, it’s worth ringing the Let Property Campaign helpline before you send the disclosure, or asking Total Books to make that call for you. HMRC is explicit about that order. A Time to Pay arrangement is assessed on what you can afford, and interest keeps running across the instalments.
Extensions are neither automatic nor generous. A landlord who has notified, started work and hit a real obstacle is still in a better position than one who has gone silent, so ask early where the window is too short.
Can I still be prosecuted after using the Let Property Campaign?
The Let Property Campaign gives no protection from prosecution. HMRC says so on the campaign guide itself.
The facility that does give that assurance is the Contractual Disclosure Facility, run under Code of Practice 9. It exists for cases involving deliberate conduct, and the assurance is the point of it.
Careless non reporting on a domestic buy to let is not a fraud case. A landlord facing a deliberate twenty year exposure is in different territory, and the route decision there should be taken before anything is notified, because it’s difficult to unwind afterwards.
Total Books is an AAT licensed practice and an HMRC registered tax agent. Cases that belong with a specialist tax investigations solicitor or a chartered tax adviser go to one from our partner network.
Two-minute check
Are you ready to notify, or is there a decision to take first?
Have you told HMRC yet that you intend to disclose?
How many years of undeclared letting income are you looking at?
How complete are the records for those years?
Which behaviour category do you think applies to you?
Has HMRC written to you about rental income?
Could you pay the tax, the interest and the penalty inside the window?
Six questions, no email address, and it tells you which of the two stages you are actually at.
See what your first fortnight involvesYour result
Your recommendation appears here.
Should I do the disclosure myself or hand it over?
Do it yourself where the facts are simple, the records are complete and the years are few. Total Books says that to people every week and means it. Hand it over where the number of years is uncertain, the records are patchy, the behaviour category is open to argument, or the sum is large enough that a percentage matters.
An agent’s work sits in three places:
- Getting the behaviour category right, which sets both the years and the range
- Rebuilding expenses properly, which reduces the tax itself
- Writing the disclosure so the telling and helping reductions are earned rather than hoped for
We act through the HMRC Agent Services Account with a signed form 64-8, so HMRC deals with us directly and the brown envelopes stop landing on your doormat. Total Books is a Companies House authorised agent and a Xero Certified Advisor firm, which is what the reconstruction work runs on.
One client wrote that Buhir “meticulously went through every step, offered helpful suggestions and patiently answered all my questions”.
★★★★★ Vanessa V. in her own words, Google review, February 2026
Once we are on record as your agent, the post about the case comes to us.
Prefer to sit down with someone? Landlords meet us in Cardiff, Newport and Bristol. Everywhere else in the UK runs through the Virtual Finance Office, with paperwork moving through the secure client portal.
Frequently asked questions
Do I have to notify HMRC before I work out the figures?
Yes. Notification comes first and the 90 day window runs from the acknowledgement, so gathering everything before you notify delays the start without protecting you.
What if I find another year after I have already submitted?
Tell HMRC as soon as you find it. A disclosure that turns out to be incomplete leaves the missing part outstanding, and correcting it yourself reads very differently from HMRC finding it later.
How long does HMRC take to accept a disclosure?
There is no published service standard. The notification acknowledgement is quick. Acceptance of the offer takes longer, and queries on individual years are the usual cause of delay.
Does making a disclosure trigger an investigation into everything else?
No. A disclosure settles the years and the tax inside it. HMRC can still open a check, and a complete, accurate disclosure is the strongest reason for them not to.
Can my spouse and I make one disclosure between us?
No. Each owner discloses their own share of the rental profit under their own reference, even where the property is jointly held and one of you handled everything.
Before you notify
Three guides that sit either side of this one, on the route, the paperwork and the letter.
Route choice
Let Property Campaign, the digital disclosure service or Code of Practice 9. Which one your facts point at.
Compare the HMRC disclosure routesMissing paperwork
What HMRC accepts when the statements stopped years ago, and how an estimate should be marked.
Disclosing with incomplete recordsNudge letters
What changes once HMRC has written about rental income, and what that ten point gap is worth.
Prompted against voluntary disclosureWhat to do next
Notify, then work. Getting those two in the right order protects the unprompted penalty range and starts a clock you can actually manage.
We handle Let Property Campaign disclosures from Cardiff, Newport and Bristol, and across the UK through our Virtual Finance Office. One client wrote that everything was explained “step by step and ensuring that my best interests were always given the highest priority”.
★★★★★ Amal E. in their own words, Google review, January 2026
Book the free 15 minute call and we’ll tell you roughly how many years you’re looking at and what the first fortnight involves.
Total Books Accountants
Start with the notification, not the boxfile
The landlord disclosure service covers the whole sequence, from the day you notify to the letter that closes the years.
Total Books Accountants Ltd is an AAT licensed practice, an HMRC registered tax agent and a Companies House authorised agent. This guide is general information about the Let Property Campaign and is not advice for a specific situation. The taxpayer remains responsible for what is disclosed to HMRC. Figures quoted in client examples are past reported outcomes for those clients, not a promise of any future result.
