5 HMO Mistakes That Cost Landlords £10,000+ in 2026

Why 2026 Is the Year HMO Compliance Gets Expensive

The Renters' Rights Act came into force on 1 May 2026. Not in theory. Not "soon." Now.

Most landlords I speak to have heard of it. Far fewer have actually updated their processes. That gap — between awareness and action — is where the fines live.

According to [footforwardproperties.co.uk](https://www.footforwardproperties.co.uk/new-fines-for-hmo-landlords-under-the-renters-rights-act/), the new civil penalty regime means serious breaches can now attract penalties of up to £40,000 per offence, while rent repayment orders have been extended from 12 months to up to 24 months' rent. That's not a slap on the wrist. That's a business-ending number for a lot of small landlords.

And councils aren't sitting on their hands. [boroughready.com](https://boroughready.com/blog/hmo-compliance-guide-2026) confirms that enforcement approaches across local authorities are actively tightening in 2026. The research notes from Just Landlords' FOI data show council enforcement actions are up 180% since 2018. Up 180%.

So here are the five mistakes I'm watching landlords make right now — with the exact financial exposure each one carries.

Mistake 1: Missing the Renters' Rights Act Information Sheet Deadline

GOV.UK guidance is explicit: landlords must issue the Renters' Rights Act Information Sheet to all existing tenants by 31 May 2026. That's 16 days from today.

Fail to do it, and you're looking at civil penalties of up to £7,000 for this category of breach — and potentially up to £40,000 for more serious non-compliance involving unlawful letting practices, per the [footforwardproperties.co.uk](https://www.footforwardproperties.co.uk/new-fines-for-hmo-landlords-under-the-renters-rights-act/) breakdown of the government's civil penalty guidance.

This one catches self-managing landlords off guard because it feels administrative. It's a piece of paper. Surely no one gets fined for a piece of paper?

They do. The government's landlord checklist is unambiguous — failure to give required written tenancy information is listed as a covered offence under the new penalty framework. And with councils now required to publish their own penalty policies, enforcement is no longer discretionary in the way it once was.

Get the Information Sheet. Send it to every tenant. Keep proof of delivery — email with read receipt, or recorded post. Do it before 31 May.

Mistake 2: Using Rent Review Clauses Instead of Form 4A

This one is catching experienced landlords out. Landlords who've had rent review clauses in their tenancy agreements for years — clauses that worked perfectly fine until 30 April 2026 — are now sitting on legally void rent increases.

From 1 May 2026, rent increases must follow the Section 13 process using Form 4A. That means a minimum two months' written notice, once per year maximum, using the prescribed form. A contractual rent review clause in your tenancy agreement does not satisfy this requirement anymore. [housingmarketnews.co.uk](https://housingmarketnews.co.uk/landlord-mistakes-under-the-new-renters-rights-act/) confirms the correct process: written notice, once per year, official Section 13 notice, two months minimum.

If you've issued a rent increase since 1 May using the old clause method, that increase is likely void. Your tenant isn't obligated to pay the higher amount. And if they've already paid it, they may have grounds to reclaim it.

I'd strongly recommend consulting a qualified solicitor to review any rent increases issued since 1 May. This isn't a grey area — it's a process change with real financial consequences.

Mistake 3: Operating Without a Valid HMO Licence in Additional Licensing Areas

Running an HMO without the required licence is, per [boroughready.com](https://boroughready.com/blog/hmo-compliance-guide-2026), one of the most serious failures in the sector. Civil penalties reach up to £30,000. Criminal prosecution carries an unlimited fine. And a banning order can stop you operating as a landlord entirely.

Here's the specific trap in 2026: additional licensing schemes.

Mandatory HMO licensing applies to properties with five or more occupants forming two or more households. Most landlords know this. What catches people is additional licensing — council-level schemes that extend licensing requirements to smaller HMOs (often three or four occupants) in specific areas. These schemes vary by borough, they're not always well-publicised, and they've been expanding.

[propertynewsdesk.co.uk](https://propertynewsdesk.co.uk/2026/01/26/5-biggest-challenges-in-residential-hmo-lettings-in-2026-and-how-to-overcome-them/) flags HMO licensing enforcement as a top challenge for 2026, noting that penalties escalate when multiple breaches occur. One licensing failure doesn't stay one licensing failure — it tends to trigger a full inspection, which surfaces every other compliance gap.

Check your council's website today. Search "[your council] additional HMO licensing scheme 2026." If your property falls within a designated area and you don't have a licence, apply immediately. The cost of the application is nothing compared to the penalty.

Mistake 4: Ignoring the Expanded Rent Repayment Order Risk

This is the one that's hitting landlords hardest right now. And it's the mistake I keep seeing.

Rent repayment orders (RROs) existed before the Renters' Rights Act. What's changed is the ceiling and the reach. Per [footforwardproperties.co.uk](https://www.footforwardproperties.co.uk/new-fines-for-hmo-landlords-under-the-renters-rights-act/), RROs now extend to superior landlords and company directors, and the maximum award has risen from 12 months to 24 months' rent in relevant cases.

On a five-bed HMO in a northern city charging £500 per room per month, 24 months' rent across all rooms is £60,000. That's not a theoretical number. That's what's at stake if a licensing or compliance failure triggers an RRO application.

The trigger events for RROs include: operating without a licence, breaching an improvement notice, and — new under the Act — a broader range of unlawful letting practices. So it's not just the fine you're managing. It's the fine plus the potential RRO running simultaneously.

If you're self-managing and you're not 100% certain your HMO is fully licensed and compliant, get a compliance audit done. Spending £300-£500 on a professional review is the cheapest insurance policy you can buy right now.

Mistake 5: Letting Safety Certifications Lapse Without a Tracking System

EICR. Gas Safety Certificate. Fire risk assessment. EPC. These aren't new requirements. But the enforcement context around them has changed.

Councils gained new investigation powers under the Renters' Rights Act. They don't need a tenant complaint to initiate an inspection anymore — they can investigate proactively. And when they do inspect, a lapsed EICR or an overdue gas certificate isn't just a paperwork issue. It's evidence of systemic non-compliance, and it opens the door to the full civil penalty range.

[boroughready.com](https://boroughready.com/blog/hmo-compliance-guide-2026) lists the compliance checklist clearly: EICR within five years, Gas Safety Certificate annually, fire risk assessment current. These aren't optional. And the fire safety requirements for HMOs go beyond a standard single-let — you need detection systems, fire doors, and emergency lighting in most cases depending on the property's HMO licence conditions.

The fix here is boring but effective: a simple compliance calendar. Every certification, every renewal date, logged in one place with 90-day and 30-day reminders. I use a spreadsheet. Some landlords use property management software. The tool doesn't matter. The habit does.

Don't wait for a tenant complaint or an inspection letter to find out your EICR expired six months ago.

Every one of these five mistakes is avoidable. None of them require specialist legal knowledge to prevent — they require attention, a system, and the willingness to treat HMO compliance as a non-negotiable operating cost rather than an optional extra.

But here's the uncomfortable truth: the landlords who get fined aren't usually the reckless ones. They're the ones who were compliant two years ago and didn't notice the rules move. The Renters' Rights Act didn't send anyone a personal memo. It just changed the game and left landlords to catch up.

The 31 May Information Sheet deadline is 16 days away. That's the most urgent item on this list. After that, check your licensing status, audit your rent increase process, and build that compliance calendar. In that order.

If you're uncertain about your specific situation — particularly around licensing or the new penalty framework — consider consulting a qualified solicitor who specialises in residential landlord and tenant law. The cost of an hour's advice is a rounding error compared to a £40,000 civil penalty.