How Many Years Do You Have To Disclose? Behaviour and Time Limits Explained

That second sentence is the one landlords are rarely told, and it’s the difference between a six year disclosure and a twenty year one.

Most people who call Total Books have never told HMRC about the rent at all. They have a tenant, a managing agent who may or may not still hold the statements, and a nagging sense that they should have done something years ago. That’s the ordinary starting position for this work.

Key takeaways

The four year rule, and why it probably is not yours

There is no single four year rule in UK tax. There are at least four separate four year periods, and landlords are routinely given the wrong one.

The question Total Books is asked most often is this one, and the answer people usually have is the ordinary assessing time limit in section 34 of the Taxes Management Act 1970. It’s the one a landlord is quoted in the pub and the one that costs them money. HMRC may raise an assessment at any time not more than four years after the end of the year of assessment it relates to. That is HMRC’s window where you took reasonable care.

The second is the overpayment relief window in Schedule 1AB, which is your window to reclaim tax you paid but did not owe. Four years again, from the end of the relevant tax year.

The third is the general claims limit in section 43, four years for claiming most reliefs. The fourth is the window for filing a late self assessment.

They all run four years from the end of the tax year, which is why they get confused. Only the first one is about how far back HMRC can come after you, and it only applies if you took reasonable care in the first place.

The four windows that actually exist

Why a failure to notify is twenty years even when you were not deliberate

Section 36(1A) of the Taxes Management Act 1970 gives HMRC twenty years in four separate situations. The first is a loss of tax brought about deliberately. The second, and this is the one that catches landlords, is a loss attributable to a failure to comply with the obligation in section 7, which is the duty to tell HMRC you are chargeable.

That second limb carries no behaviour test. It does not say deliberately. It applies because you did not notify, full stop.

Total Books has yet to meet a landlord who was told this by anyone else. HMRC’s own guidance states it plainly: the time limit for failure to notify is twenty years, whether or not the failure was deliberate. The published table of time limits has no six year row for failure to notify. Carelessness does not bring you down to six once you never registered at all.

In practice this catches the most ordinary landlords on the list. Someone who let one flat to a single tenant, took the rent into a personal account, never asked for a UTR and never saw a brown envelope, is on the same twenty year clock as a landlord who knew exactly what they were doing.

This is the point that separates a competent disclosure from an expensive one, because a landlord who assumes six years and submits six years has submitted an incomplete disclosure, and HMRC treats a materially incomplete disclosure very differently from a full one.

That’s where Total Books draws the line. We do not build a disclosure pack on the six year assumption unless the Self Assessment record proves the landlord was registered on time. Talk to a person, not a chatbot, and the first question you’ll be asked is whether you ever had a UTR.

So behaviour does not matter?

It matters a great deal. It just does a different job, and Total Books assesses the two separately.

Behaviour drives the penalty rate. The failure to notify drives the number of years. A landlord who never registered and was simply disorganised is still in the twenty year window, but sits in the non-deliberate penalty band rather than the deliberate one, which is the difference between roughly a fifth of the tax and roughly half of it.

Total Books maps this year by year before anything is notified. Once you register and start filing, later years come back inside the normal limits, because you are no longer in breach of section 7. So the same disclosure can legitimately carry a twenty year tail and a six year head. That’s not inconsistent. It is the rules applied year by year, which is how they are meant to be applied.

One file per year

Twenty years is not twenty times harder. It is the same year, done twenty times.

What the limits run from

Every one of these periods runs from the end of the year of assessment, not from the date the tax was due and not from the day HMRC found out.

The UK tax year ends on 5 April. So the clock starts on 5 April, not on the following 31 January. Articles that say “six years from when the tax was due” are out by about ten months, and on a borderline year that error changes whether a year is in or out.

What you will need for each of those years

Whatever the window turns out to be, the work is the same shape for every year inside it: the rent received and the allowable expenses.

In practice that means the letting agent statement or the rent book, the bank statement showing what actually arrived, the mortgage interest certificate, and the tenancy agreement for the dates. The deposit scheme record helps where a tenant moved mid-year, and a void period has to be accounted for rather than averaged away.

Twenty years of that is a real exercise, and it is why Total Books settles the years question first, and it’s the reason the years question is worth settling first. A landlord with a portfolio has it several times over. A landlord with one buy to let has it once, across more years than they expected.

Where the early paperwork has gone, HMRC accepts a reasoned estimate with the workings kept, so missing records lengthen the job without stopping it.

The years a disclosure made now actually reaches

Work the arithmetic and it becomes concrete. For a disclosure made at any point between 6 April 2026 and 5 April 2027:

There is a wrinkle on the oldest years. For income tax, the twenty year failure to notify limit does not reach back into 2008-09 and earlier on its own. For those three earliest years HMRC needs the older test of negligent conduct. In practice a landlord who said nothing for twenty years is rarely found to have been anything other than negligent, so 2006-07 is usually reachable, but the qualifier is real and it’s worth knowing.

The date you disclose matters less than you think, and then suddenly matters a lot

Because the limits run from 5 April, the range does not creep forward day by day. A disclosure made on 30 November 2026 reaches exactly the same years as one made on 4 April 2027.

Then on 6 April the whole range steps forward by a full year, and the oldest year drops out of each band at once.

That is worth knowing. It means there’s no advantage in rushing a disclosure out in March at the cost of getting it wrong. It also means a landlord who drifts from March into April has quietly changed the shape of their disclosure.

The asymmetry nobody mentions

Here is the position we will defend, because landlords are routinely surprised by it late in the process.

Where HMRC’s window extends to six, twelve or twenty years, your window does not extend with it. The overpayment relief limit stays at four years. So a landlord disclosing fifteen years of rent cannot simply reach back fifteen years and claim fifteen years of missed expenses, finance cost relief and losses as of right.

The years run further one way than the other. This is exactly why the expenses position on the early years needs working properly inside the disclosure itself, where it counts, rather than being left to a later claim that cannot be made.

Are you liable for your accountant’s mistake?

Yes, in the sense that matters here. Section 36(1B) says a loss brought about by another person acting on your behalf counts as a loss brought about by you.

So a landlord whose managing agent never sent the statements, or whose previous accountant was told about the rent and left it off the return, is still inside the extended window. You may have a separate argument with that adviser. You don’t have one with HMRC on the time limits.

The way out of twenty years, and how narrow it is

Total Books tests this on every case where the landlord never registered. There is one route from the twenty year failure to notify window back to four, and it is reasonable excuse under section 118(2).

HMRC defines a reasonable excuse as something that stops a person meeting a tax obligation despite them having taken reasonable care to meet it. There is no statutory list. The excuse has to exist on or before the due date, continue through the period of default, and the failure has to be put right without unreasonable delay once the excuse ends. The burden is on you.

Not knowing that rental income is taxable does not clear that bar on its own. It is at best carelessness, and carelessness still leaves you in the twenty year window once you never notified. The route exists. It is narrow, it is fact-specific, and it isn’t the answer for most landlords.

Window first

Let Property Campaign service

We read the Self Assessment record before we name a number of years

The registration date decides the window. We check it first, then build the schedule year by year, then agree the behaviour position with you.

See how the window is set

Overseas property and the twelve year limit

Total Books treats an overseas property as an open question until it has been checked. If the property is abroad, or the income has an offshore element, there is a separate twelve year limit that sits between careless and deliberate. It applies whether you took reasonable care or were careless. The records question is harder too, because a foreign managing agent rarely issues anything that looks like a UK letting agent statement and the bank statement may be in another currency.

GOV.UK’s public guidance on the campaign does not mention this limit at all. A landlord with an apartment in Spain reading that page would conclude they are on four or six years when they may be on twelve. If that is your position, start with our guide to double taxation relief on foreign rental income and treat the years question as open until it has been checked.

Two situations, worked through

A landlord let a terraced house from 2011 after moving in with a partner. He never registered, assuming the mortgage interest cancelled out the rent. It didn’t, and after the finance cost rules changed it did so even less. Because he never notified, every year from 2011 sits inside the twenty year window. His behaviour was non-deliberate throughout, so the penalty band is the gentle one, but the disclosure pack covers fourteen years rather than the six he had budgeted for.

A second landlord had filed the return since 2018 and declared the rent on three of them but not the other four. She was already registered and had a UTR, so section 7 was never breached. Her exposure runs on the careless limit, six years, and the earliest year she has to reach is 2020-21. Same amount of undeclared rent, half the number of years, because one of them registered and the other didn’t.

Both are illustrative and modest. Yours depends on when you first let and what you did about it.

Frequently asked questions

About Total Books

Total Books is an AAT licensed practice and an HMRC registered tax agent, acting for landlords, directors and small businesses across Cardiff, Newport and Bristol. We are also a Companies House authorised agent and a Xero Certified Advisor, and we hold an HMRC Agent Services Account for ongoing Self Assessment work. Records come to us through a secure client portal rather than by email, and every disclosure starts with the same free 15 minute call.

Where to go next

Total Books settles the years question before anything is notified, because it sets the size of everything else, so it’s worth settling before you notify. Once you know the range, our step by step guide to the disclosure covers the sequence, and if the paperwork for the older years has gone, read disclosing with missing records before you assume the early years are impossible.

Bring us the date you first let the property and whether you’ve ever been registered for Self Assessment, and Total Books will tell you which window applies. Book the free 15 minute call. Talk to our Let Property Campaign team

Total Books is an AAT licensed practice and an HMRC registered tax agent, acting for landlords across Cardiff, Newport and Bristol.