Since the Renters’ Rights Act came into force on 1 May 2026, a lot of the guarantor conversation on here has focused on one fear. Now that fixed terms are gone and every tenancy is periodic, is the guarantor locked in for life? It is a fair worry. But in my work on tenancy and possession matters I keep seeing the risk pointed the wrong way round. The quieter danger is not that your guarantor is trapped forever. It is that you could release them by accident, and the most likely moment you do it is the day you put the rent up.
I want to walk through why, what the law actually says, and why none of this is as settled as either side of the argument tends to claim. I am not going to tell you what your guarantee does, because that depends entirely on the document you hold. I am going to suggest what to check.
This article is for general information purposes only. It does not constitute legal advice. Guarantee law is highly fact-sensitive, and the outcome in any case turns on the exact wording of the document in question. Landlords should seek independent legal advice for their specific circumstances, particularly where tenancy or guarantor arrangements are complex.
The old rule that still has teeth
The starting point is a Court of Appeal decision from 1878, Holme v Brunskill. The principle that came out of it is often called the variation rule. In broad terms, if the contract that a guarantee supports is varied without the guarantor’s consent, the guarantor may be discharged from liability, unless the variation is self-evidently insubstantial or could not possibly prejudice them.
The courts have applied that principle well beyond its Victorian origins. The point that matters for landlords is this. A guarantor agreed to stand behind a particular set of obligations. If those obligations change in a way that could be to the guarantor’s disadvantage, and they did not agree to the change, a court may treat the guarantee as discharged.
You can see why a rent increase sits close to the firing line. A higher rent is, on its face, a larger exposure for the guarantor than the one they originally agreed to. Whether a court would treat any given increase as a discharging variation is not something I can promise either way. But it is the kind of change the rule was designed to catch.
Why this collides with the new rent rules
Under the Act, there is now a single route to increasing the rent on an assured periodic tenancy. You serve the statutory Section 13 notice on the prescribed form, you can do this once a year, and you propose the market rent giving at least two months before it takes effect. Rent review clauses written into older agreements no longer do the job. GOV.UK guidance is explicit that rent increases by other means, including rent review clauses, are not permitted.
So the position many landlords are now in is that they will be raising rents more deliberately, and through a formal annual notice, precisely because the old contractual mechanisms have fallen away. Every one of those notices is a moment when the guarantor question is live.
Here is the honest caveat. There is a genuine argument that a rent increase imposed through the statutory Section 13 process is not a contractual variation in the Holme v Brunskill sense at all, because it is not something the landlord and tenant have agreed between themselves. It is imposed through a statutory mechanism. I have not seen that point tested in the courts in the specific context of the new system, and I would be wary of anyone who tells you the answer is obvious in either direction. What I can say is that it appears to be unresolved, and unresolved is not the same as safe.
It comes down to the wording of the deed
Whether a guarantee survives a rent increase, or survives the move from a fixed term to a periodic tenancy on 1 May, may turn almost entirely on how the document was drafted.
Well drawn guarantees usually contain what lawyers call anti-discharge or consent to variation provisions. These are clauses saying, in effect, that the guarantor’s liability continues even if the rent or the terms change. On the face of it those clauses do their job. The complication is that they tend to be read strictly against the landlord, as the party who put the clause forward, under what lawyers call the contra proferentem rule. Courts have also limited how far such clauses can stretch, holding in some cases that they may not cover a change going beyond what the original guarantee was ever meant to encompass. So a clause that looks watertight is not, by itself, a guarantee of a guarantee.
There is a second layer where the guarantor is an ordinary individual rather than a business. Where the guarantor is acting as a consumer, the fairness rules in the Consumer Rights Act 2015 can apply, and a court must take the fairness of the term into account. A clause binding a private individual to an open ended and growing liability, with no way out, is the kind of term that could attract scrutiny. I am not saying it would fail. I am saying it is not a question you want to be discovering the answer to in a possession hearing.
What I would consider doing
None of this means guarantees are worthless. It means the document, and the paper trail around it, may matter more than they used to.
If it were my portfolio, I would think about four things. I would have the guarantee itself looked at by someone who does this for a living, rather than assuming a form downloaded years ago still does what I need. I would check whether it was drafted to extend to a periodic tenancy, and to survive rent changes, in clear terms. I would keep the signed deed, any explanatory information given to the guarantor, and the copy of the tenancy agreement they were shown, all dated and together. And whenever I served a rent increase, I would consider notifying the guarantor in writing and keeping proof that I did, so that if the consent question ever arose I would not be relying on memory.
None of this requires any particular tool. But it does require a habit. A guarantee you cannot evidence, attached to changes the guarantor was never told about, is a guarantee on shaky ground.
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At LLCR, I built tools aimed squarely at this problem. The free Form 4A rent increase generator produces a Section 13 notice on the prescribed form and flags the timing rules before you serve. Alongside it, LLCR gives self-managing landlords a single place to store the guarantee deed, the information the guarantor was given, and a dated record of every rent change they are notified of. Each file is timestamped at upload and tamper evident, so if the consent question is ever raised, you can show what existed, in what form, and when, rather than relying on memory.
Not sure where your exposure sits? LLCR’s free compliance checker runs through the legal requirements for your tenancy in minutes.
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None of this means guarantees are not worth taking. It means the document, and the trail of evidence around it, may matter more than they ever did under the old system. If you are relying on a guarantee signed years ago, the ten minutes it takes to read it again, and to check it was written to survive both the move to a periodic tenancy and a rent increase, may be the most useful ten minutes you spend this year.
I would be interested to hear from anyone who has actually tried to enforce a guarantee after a rent increase under the new system, or who has had the periodic transition argument run against them. Has anyone had a guarantor try to walk away on the back of Holme v Brunskill? And for the letting agents here, have you redrafted your guarantee deeds since 1 May, and if so, how?
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Tauhid Islam is a property law paralegal qualifying as a solicitor. He works on tenancy, possession, and compliance matters daily, and founded LLCR, Landlord Compliance Register, to give self-managing landlords in England a single place to track every deadline, certificate, and document the law requires of them.
This article is for informational purposes only and does not constitute legal advice. Always seek independent legal advice for your specific situation.
