Five Common MTD Reporting Errors That Trigger HMRC Investigations For Landlords
Five Common MTD Reporting Errors That Trigger HMRC Investigations for Landlords
Landlords most often draw HMRC's attention under Making Tax Digital for Income Tax (MTD IT) by getting the qualifying income threshold test wrong, submitting quarterly updates that do not reconcile with their bank records, miscategorising expenses, keeping records that are not properly digitally linked, or misreporting jointly owned property income. For the 2026/27 tax year, any one of these can trip HMRC's automated cross-checks and prompt a compliance check.
MTD IT became mandatory from 6 April 2026 for anyone with gross income from property and self-employment above £50,000, based on their 2024/25 tax return figures. That threshold falls to £30,000 from April 2027 and £20,000 from April 2028, each measured against the tax return two years earlier. Under the new system, HMRC no longer waits until 31 January the following year to see your figures. It sees a running picture of your income and expenses four times a year, and that changes what "getting it wrong" looks like. A mistake that used to sit quietly in an annual return until an accountant caught it now shows up in real time, sometimes in a pattern across two or three quarters before anyone notices.
I have spent sixteen years watching landlords adjust to changes in how HMRC collects information, and MTD IT is the biggest shift of that period. The errors below are not exotic. They are the ones I see repeatedly, and they are the ones most likely to generate a nudge letter, a targeted query, or a full compliance check.
Error One: Getting the Qualifying Income Threshold Test Wrong
The most basic error is also the most consequential, because it decides whether you should be in MTD IT at all. HMRC's guidance confirms that qualifying income for the threshold test is gross income from self-employment and property combined, before any expenses are deducted, and it is measured against the tax year two years before the one in which MTD starts. Landlords frequently miscalculate this in one of three ways.
First, they net off expenses before comparing their income to the threshold, which understates the figure and can lead them to believe, wrongly, that they are outside MTD when HMRC's own records say otherwise. Second, they overlook that self-employment and property income must be added together, so a landlord with £29,000 of rental income and £25,000 from freelance work is over the £50,000 threshold even though neither source alone would trigger it. Third, jointly owned property causes real confusion: your threshold is based on your own share of the rental income, not the total rent the property generates. A property producing £60,000 in rent, split 50:50 between you and your spouse, gives each of you £30,000 of qualifying income from that source, not £60,000 each.
Because HMRC identifies who is mandated using data already on file from your Self Assessment return, a landlord who has understated income in the past, deliberately or otherwise, may find HMRC's system places them into MTD IT a year earlier or later than they expect, or flags a discrepancy when their MTD submissions do not match the profile HMRC built from prior returns. You can check your own position against the official criteria on the <a href="https://www.gov.uk/guidance/check-if-youre-eligible-for-making-tax-digital-for-income-tax">GOV.UK guidance on eligibility for Making Tax Digital for Income Tax</a>, and it is worth doing that calculation properly rather than estimating it.
Error Two: Quarterly Updates That Do Not Reconcile
Under MTD IT, each quarterly update is cumulative. The update due 7 August covers 6 April to 5 July, the one due 7 November covers 6 April to 5 October, and so on, with each submission replacing rather than adding to the last. This structure catches landlords out in a specific way: an error in the first quarter does not stay contained to that quarter. It carries forward, distorting every subsequent update until someone corrects it, and by the time the annual declaration is due the discrepancy between the running total HMRC has received and what the actual bank statements show can be substantial.
HMRC's systems increasingly cross-reference the income figures in quarterly updates against third-party data, including information from letting agents, tenancy deposit schemes, and, since Confirmation of Payee and open banking data-sharing initiatives expanded, bank account information in some cases. A landlord who reports rent received on a cash basis but whose agent reports gross rent collected before deducting a management fee will show a mismatch that HMRC's system can flag automatically, without a human ever looking at the file first. This is the kind of discrepancy that starts as an automated query and becomes a full check if the response is vague or late.
The practical fix is not complicated. Reconcile your quarterly figures against your bank statements and any agent statements before you submit, every time, not just at year end. If a figure needs correcting from a prior quarter, correct it in the next cumulative update rather than leaving it and hoping the annual declaration smooths it out. The penalties guidance on GOV.UK confirms that HMRC will not issue penalty points for late quarterly updates during the 2026/27 transitional year, but that soft landing covers lateness, not accuracy. Getting the numbers wrong is a separate and, in my view, more serious problem than getting them in late.
What this Widget is About: Created by My Tax Accountant, this interactive explainer helps UK landlords navigate Making Tax Digital for Income Tax (MTD IT) by highlighting the five most frequent compliance errors that attract automated HMRC investigations. Inside, you can explore the phased gross income thresholds, test your mandate date with the built-in threshold calculator, and verify tricky reporting rules surrounding joint property ownership and expense categorisation. Simply click through the error cards and interactive tools to assess your tax reporting risks, ensure your digital records reconcile seamlessly, and safeguard your property business before quarterly submissions begin.
Error Three: Miscategorising Expenses Under Property Income Rules
MTD software forces landlords to categorise every transaction, and this is where old habits from spreadsheet-based Self Assessment returns cause the most damage. A landlord used to lumping "repairs and maintenance" together in one figure for their accountant to sort out at year end now has to make that categorisation decision quarter by quarter, transaction by transaction, often without professional oversight at the point of entry.
The distinction that causes the most trouble is capital versus revenue expenditure.
Replacing a broken boiler is generally a revenue repair. Installing a boiler in a property that never had one, or upgrading to something materially better than what was there, tips into capital expenditure and is not deductible against rental income in the same way. HMRC's Property Income Manual sets out this distinction in detail, and it has not changed under MTD, but the frequency of reporting means a wrong categorisation now appears in HMRC's data four times a year rather than once, giving HMRC's risk-profiling tools more data points to notice a pattern.
The other recurring error is finance cost treatment. Residential landlords cannot deduct mortgage interest as an expense against rental income; instead they get a basic rate tax reduction on that finance cost, applied after profit is calculated. I still see landlords enter mortgage interest as a straightforward expense in their software because that is what the transaction looks like on a bank statement, which understates their taxable profit in every quarterly update and then requires a correction at the annual declaration stage that draws attention to itself. If you have both residential and furnished holiday let income, note that the treatment differs and needs to be kept clearly separated within your digital records from the outset.
Error Four: Digital Records That Are Not Properly Linked
MTD IT requires digital record keeping with digital links between the point of entry and the final submission. This does not mean you must abandon a spreadsheet. It means that if you use one, the data must flow into your MTD-compatible software through an approved digital link, such as an API-enabled bridging tool, rather than being manually retyped.
The error I see most often here is not a design flaw in anyone's system but a habit: a landlord keeps a spreadsheet, updates it carefully, and then manually re-enters the totals into their software at the end of each quarter because that feels like the easier step. This breaks the digital link requirement and, more practically, introduces transcription errors that would not occur with an automated feed. A rounding error repeated across four quarters, or a figure copied from the wrong column, becomes a pattern in HMRC's data that looks like inconsistency, and inconsistency over several quarters is exactly the kind of signal that moves a case from routine to worth a closer look.
There is a related point worth flagging plainly: not keeping adequate digital records at all, rather than merely keeping them imperfectly, exposes you to a separate penalty regime. This is a compliance failure HMRC treats seriously precisely because the entire architecture of MTD depends on the underlying records being genuinely digital, not retrofitted at quarter end from a paper diary or a set of receipts in a shoebox.
Error Five: Getting Jointly Owned Property Income Splits Wrong
Joint ownership is common among landlords, and MTD IT applies to each owner individually based on their own share of the income, which means each person's submissions need to reflect the correct split, consistently, quarter after quarter. Two things go wrong here repeatedly.
The first is the married couples' default. Where a property is owned jointly by spouses or civil partners, income tax law treats the rental income as split 50:50 regardless of the actual ownership proportions, unless a valid election has been made to HMRC using Form 17, supported by evidence of the true beneficial ownership such as a declaration of trust. This 50:50 default rule is set out in Chapter 3 of Part 5 of the Income Tax Act 2007. I have seen couples who own a property 90:10 in favour of the lower earner, for entirely sensible reasons connected to who put in the deposit, continue reporting quarterly figures on that 90:10 basis without ever having filed a valid Form 17, which means HMRC's position, if it ever checks, is that the 50:50 default applies and both parties have been misreporting their income for as long as the arrangement has run. Form 17 cannot be backdated, so this is not a mistake you can quietly correct once it is noticed; it has to be fixed going forward, and prior years may need review.
The second is joint ownership between people who are not married or in a civil partnership, such as siblings or business associates. Here the default is different: income follows actual beneficial ownership from the outset, with no automatic 50:50 assumption, but landlords in this position often assume the same married-couple rule applies to them and end up reporting an even split that has no legal basis, simply because that is what they have seen other landlords do. Each co-owner's quarterly updates and threshold calculation should reflect their genuine entitlement, evidenced in writing, from day one.
A Worked Example
Take a landlord couple who jointly own two rental properties as tenants in common. One property is held 50:50 and generates £34,000 in gross rent for the 2026/27 tax year. The second is held 80:20 in favour of the wife, evidenced by a declaration of trust and a valid Form 17 filed in 2019, and generates £22,000 in gross rent. The husband's qualifying income from property is £17,000 (his half of the first property) plus £4,400 (his 20% share of the second), totalling £21,400. The wife's is £17,000 plus £17,600, totalling £34,600. If the husband also earns £30,000 from freelance consultancy, his combined qualifying income is £51,400, which puts him into MTD IT from April 2026 even though his wife, with the higher property income alone, would not yet be mandated on the property figures if she had no self-employment income and her total sat below £50,000. Each spouse's MTD position has to be worked out separately, on their own figures, not on the combined household income.
What this Widget is About: This interactive explainer highlights the five most common Making Tax Digital for Income Tax reporting mistakes that can trigger HMRC attention for UK landlords, from misjudging the qualifying income threshold to incorrect joint-ownership splits and poorly linked digital records. Simply click each numbered heading to expand clear, practical guidance on what goes wrong, why it matters, and how to avoid it, complete with a worked example and a quick checklist. The content is designed for easy reading on any device and reflects the latest official rules so you can check your position with confidence before your next quarterly update.
Why These Errors Escalate Into Investigations
None of these five errors, on its own, guarantees a compliance check. What tends to escalate a case is a pattern: a threshold miscalculation combined with inconsistent quarterly figures, or a categorisation error that recurs every quarter rather than appearing once. HMRC's risk profiling under MTD is built around exactly this kind of pattern recognition, because the whole point of quarterly reporting is to give HMRC more data points across the year rather than one annual snapshot. A single wrong figure, corrected promptly and explained if asked, is usually just that. A wrong figure repeated across four quarters, alongside a threshold calculation that does not match HMRC's own records, looks like something else entirely, and that is where a routine automated flag turns into a letter asking for supporting evidence.
If you are approaching MTD IT for the first time in April 2026 or April 2027, the practical priority is to get your threshold calculation right before you do anything else, set up a genuinely digital record-keeping routine rather than a hybrid one, and reconcile every quarterly update against your actual bank and agent records before you submit it. Where property is jointly owned, resolve the correct split and, if needed, file Form 17 properly before your first quarterly deadline rather than after HMRC has queried it.
Scottish and Welsh Positions
MTD IT itself is a UK-wide administrative requirement and applies identically to landlords in Scotland, Wales, England, and Northern Ireland; the thresholds, quarterly deadlines, and penalty rules do not vary by nation. Where confusion does arise is on the tax rate applied to the profit once it is calculated. Property income is not devolved and continues to be taxed using the main UK non-savings, non-dividend rates and bands, even for a landlord who is a Scottish taxpayer paying Scottish rates on their employment or pension income.
I regularly see Scottish landlords assume their rental profit is taxed at Scottish rates simply because they submit a Scottish tax return; it is not, and getting this wrong affects the payment calculation even where the MTD reporting itself was accurate. Welsh taxpayers are taxed on UK rates for all non-savings, non-dividend income including property, since the Welsh rates of income tax to date have been set to mirror the rest of the UK, but this is a policy choice that could change in a future Welsh Budget, so it is worth checking each year rather than assuming.
FAQs
Do I need to join MTD for Income Tax if my only income is rental income?
Yes, if your gross rental income (your own share, not the total for a jointly owned property) exceeds the relevant threshold for the tax year being tested. There is no exemption simply because you have no self-employment income; property income alone is enough to bring you into scope once it passes £50,000, £30,000, or £20,000 depending on the year.
What happens if I miscalculate my qualifying income and I am actually over the threshold?
If HMRC's own records show you should have been in MTD IT and you were not, you may be treated as non-compliant from the date you should have joined, which can bring both record-keeping and submission failures into scope, not just the threshold error itself. It is worth checking your position properly rather than assuming.
Is there a penalty for a wrong figure in a quarterly update, separate from being late?
The points-based penalty system in place from 2026/27 primarily targets lateness, and quarterly updates carry no penalty points during the 2026/27 transitional year specifically for being late. Persistent inaccuracy is a different issue and can lead to a compliance check and, depending on the circumstances, penalties for inaccurate returns under the existing Self Assessment inaccuracy penalty regime.
Can I still use a spreadsheet under MTD for Income Tax?
Yes, provided it is connected to HMRC-recognised software through a digital link, such as bridging software, so that figures are transferred automatically rather than retyped. A spreadsheet used purely as a personal record, with totals manually keyed into separate software, does not meet the digital record-keeping requirement.
Do I need to file Form 17 if my spouse and I own a property 50:50?
No. Form 17 is only needed where you want HMRC to tax you on a split other than the default 50:50 position for married couples and civil partners. If your actual ownership and the tax treatment you want are already 50:50, no election is required.
Does MTD change how mortgage interest is treated for landlords?
No, the underlying rule is unchanged: mortgage interest and other finance costs on residential lets are not deducted as an expense against rental profit but instead attract a basic rate tax reduction after profit is calculated. What changes under MTD is the frequency with which a wrong entry, such as recording interest as a straightforward expense, gets reported to HMRC.
I am a landlord in Scotland. Does MTD threshold or process differ from England?
No. The thresholds, quarterly deadlines, digital record-keeping requirements, and penalty rules under MTD IT are identical across the UK. What differs is the income tax rate applied to your other, devolved income sources, such as employment; your rental profit itself is taxed using UK rates regardless of where you live.
If I jointly own a property with my adult child rather than my spouse, does the 50:50 default apply?
No. The automatic 50:50 rule applies only to married couples and civil partners who live together. Joint owners in any other relationship, including parent and adult child, siblings, or unrelated business partners, are taxed according to their actual beneficial ownership shares from the outset.
What triggers an HMRC compliance check under MTD specifically, rather than a general Self Assessment enquiry?
A pattern across quarterly updates that does not reconcile with third-party data HMRC holds, such as letting agent reports or figures from a previous year's return, is the most common trigger. A single quarter with an unusual figure is less likely to prompt action than a consistent discrepancy running across several submissions.
If I realise I have made an error in an earlier quarterly update, what should I do?
Correct it in your next cumulative quarterly update rather than waiting for the annual declaration, since each update replaces the running total for the year to date. If the error is significant or spans a prior tax year already finalised, it is worth taking advice on whether a separate disclosure or amendment is needed.
About the Author
Maz Zaheer, AFA, MAAT, MBA, is the CEO and Chief Accountant of MTA and Total Tax Accountants, two premier UK tax advisory firms. With over 15 years of expertise in UK taxation, Maz provides authoritative guidance to individuals, SMEs, and corporations on complex tax issues. As a Tax Accountant and an accomplished tax writer, he is renowned for breaking down intricate tax concepts into clear, accessible content. His insights equip UK taxpayers with the knowledge and confidence to manage their financial obligations effectively.
Disclaimer:
This article explains the general position for the 2026/27 tax year and is accurate at the date of publication. Tax outcomes depend on individual circumstances, and rules change. It is not advice for your situation. For guidance on your own position, speak to a qualified accountant or tax adviser. My Tax Accountant accepts no liability for action taken solely on the basis of this article.
