How Landlords Can Legally Raise Rent (and Why Bidding Wars Are Now Banned)

Four parts of the Renters' Rights Act 2025 work together to reshape how rent is set, collected, and increased in the private rented sector. Bidding wars are banned. Rent in advance is capped at one month. Section 13 with the new Form 4A is the only route to a rent increase. And the First-tier Tribunal has lost the power to backdate rent increases or set rents above the landlord's proposed figure. Together, these changes alter the economics of letting in ways that landlords need to plan around — not just comply with.

The four connected changes

Most coverage of the Renters' Rights Act treats rent rules as a list of separate items. In practice, they form a coherent regulatory framework with one purpose: to remove pricing power from the letting moment and constrain how it can be exercised during the tenancy.

• Bidding wars are banned — under sections 55 and 56 of the Act. Landlords must publish an asking rent in written advertising; offers above that figure cannot be solicited or accepted.
• Rent in advance is capped at one month (or 28 days for sub-monthly tenancies). The cap applies after the tenancy agreement is signed; nothing can be required before signing.
• Section 13 is the only route to a rent increase. Contractual rent review clauses are unenforceable. Section 13 notices require the prescribed Form 4A, two months' notice, and at most one increase per twelve-month period.
• The First-tier Tribunal has been re-engineered. The Tribunal can only confirm or reduce a proposed rent — never increase it. Approved increases take effect from the determination date, not the original notice date. There is no backdating.

Each change individually is significant. The combined effect is a fundamental shift in how rent works as a commercial proposition, particularly for landlords whose business model relied on flexibility at the letting moment or aggressive in-tenancy increases.

The bidding wars ban

From 1 May 2026, written advertising of any property for letting on an assured tenancy must include a specific asking rent. The provision is in chapter 6 of part 1 of the Renters' Rights Act 2025, with civil penalties enforceable by local housing authorities. The framework is straightforward but the practical implications are wider than landlords often realise.

What the rule prohibits

Three behaviours are now unlawful:

• Advertising without a stated rent. Any written advertisement (online listing, printed brochure, social media post, agency window display with detail) must state the asking rent. The single exception is a sign at the property merely stating the property is available — no further detail.
• Inviting or encouraging offers above the asking rent. A landlord or agent cannot ask prospective tenants to bid, organise an auction-style process, or hint that the property will go to "the best offer". The offence is in the conduct, not in the outcome.
• Accepting offers above the asking rent. Even where the tenant volunteers a higher offer without prompting, the landlord cannot accept. The asking rent is a ceiling, not a floor.

The penalty is a civil penalty of up to £7,000 per breach, imposed by the local authority. Repeat breaches within a five-year period attract additional penalties. The local authority is under a statutory duty to enforce — not a discretion — and breaches are recorded on the forthcoming Private Rented Sector Database. This is enforcement architecture designed to be used.

Practical consequences for advertising

The market response to the bidding wars ban is likely to be threefold:

• Asking rents will be set higher. Landlords who previously underpriced to attract bids will now post the rent they actually want. In genuinely competitive areas, this produces no real change in the rent achieved — just less ambiguity at the listing stage.
• Tenant pre-screening becomes more important. The price filter has lost some of its power, so referencing, affordability assessment, and guarantor arrangements take on more weight in choosing between competing applications.
• Some informal practices become risky. "We've had several offers — what's your best?" was a routine letting-agent line; under the new rules it is straightforwardly a breach. Agents will need to retrain client-facing staff.

Industry commentary has noted that enforcement will be challenging — bidding wars often happen in private exchanges that local authorities cannot easily monitor — but the legal position is clear and the penalty regime is real.

The advance rent cap

For tenancies signed on or after 1 May 2026, no more than one month's rent (or 28 days' rent for tenancies with rent periods of less than one month) can be required as advance payment. The rule is set out in the Renters' Rights Act and amends the Housing Act 1988 with a related prohibition on enforcing any tenancy clause requiring rent in advance of the agreed due date during the tenancy.

Three timing points matter:

• Nothing can be required before the tenancy agreement is signed. Pre-signing demands for advance rent are prohibited. (A holding deposit capped at one week's rent under the Tenant Fees Act 2019 remains permitted.)
• One month's rent can be required at the moment of signing. This is the standard "first month in advance" model — preserved within the new cap.
• During the tenancy, advance rent cannot be required. A clause stating "rent payable quarterly in advance" or similar is unenforceable. Tenants can voluntarily pay in advance once the tenancy has started, but cannot be required to.

The most consequential change is for landlords who have relied on six-or-twelve-month advance rent to mitigate credit risk for tenants with thin credit files — international students, recent graduates, tenants without UK employment history. That route is closed for new tenancies signed from 1 May 2026.

The replacement strategies are guarantor arrangements, rent guarantee insurance, and tighter affordability assessment. None of these is as straightforward as a six-month upfront payment, and there are tenant categories (mainly international students) where the practical impact is significant. Some landlords will respond by tightening referencing criteria; some will simply decline to let to higher-credit-risk tenants. The latter behaviour, where it correlates with characteristics protected by the Renters' Rights Act discrimination provisions (children, benefits recipients), will itself attract civil penalties.

Existing arrangements under tenancies signed before 1 May 2026 remain valid for the duration of that specific tenancy. A tenant who has paid six months in advance under a pre-1-May tenancy does not get a refund; the existing contractual position holds until the tenancy ends.

Section 13 is the only route to a rent increase

Contractual rent review clauses — RPI-linked, CPI-linked, fixed-percentage uplifts — become unenforceable for assured tenancies on 1 May 2026. Section 6 of the Renters' Rights Act amends the Housing Act 1988 to make Section 13 the exclusive mechanism for raising rent on an assured periodic tenancy.

The headline rules for Section 13 post-RRA:

• Once per twelve-month period. The clock runs from the date of the previous Section 13 increase, or from the start of the tenancy if there has not yet been one.
• Two months' notice. The notice period has doubled from the pre-RRA position of one month.
• Form 4A is the prescribed form. It replaces the previous Form 4. Notices on the old form served on or after 1 May 2026 are invalid.
• The proposed rent must be at the open market rate. Tribunal challenge is the test, not what the landlord believes the property is worth.

The procedural detail of how to complete and serve Form 4A — including the notice arithmetic for non-monthly tenancies, the prescribed information about challenge rights, and the practical guidance on proof of service — is covered in our Section 13 rent increase guide. That page is the procedural manual; this page focuses on the strategic implications.

The new tribunal regime: where the real change is

The First-tier Tribunal (Property Chamber) has been reformed by the Renters' Rights Act in ways that fundamentally change the calculus of rent disputes. These changes are easy to miss in summaries that focus on bidding wars and Section 13, but they may matter more in practice than either.

What changed

Three reforms transform the Tribunal from a deterrent on tenant challenges into something close to a free option:

• The Tribunal can only confirm or reduce — never increase. Pre-RRA, if the Tribunal found the open market rent was higher than the landlord's proposed figure, it could (in some circumstances) set the rent at the higher market figure. Post-RRA, the landlord's proposed figure is a ceiling: the Tribunal can confirm it or set a lower figure. The tenant has no risk of paying more by challenging.
• No backdating. Pre-RRA, when the Tribunal upheld an increase, the new rent applied retrospectively from the original notice date — meaning tenants who challenged unsuccessfully often faced months of arrears. Post-RRA, the new rent applies only from the date of the Tribunal's determination. The tenant pays the old rent throughout the challenge period.
• Hardship deferral. The Tribunal can defer the new rent by a further two months beyond the determination date in cases of "undue hardship" for the tenant.

The procedural side: tenants must apply to the Tribunal before the Section 13 notice expires. The application fee is £47 (announced by government in March 2026, subject to regulations). Tribunals decide either on paper or after an oral hearing, and provide reasons.

The strategic consequences for landlords

Industry surveys before the Act commenced indicated that around one in five tenants intended to challenge any rent increase, regardless of whether they considered it fair, simply because there was no longer any downside to doing so. Whether or not that figure proves accurate, the rational tenant calculus has clearly shifted: challenging is free (or nearly free), risk-free (no possibility of higher rent), and produces months of continued lower rent during the challenge.

For landlords, three implications follow:

• Tribunal challenges will become routine. They were rare pre-RRA (around 1,500 applications nationally in 2024-25). The combination of zero risk and meaningful upside will increase application numbers materially. Tribunal capacity is a real constraint; backlogs are likely.
• Effective rent increases happen later than expected. A landlord who serves a Section 13 notice on 1 November 2026 for an effective date of 1 January 2027 may not see the higher rent take effect until the Tribunal hearing date (potentially mid-2027 or later). The arithmetic of when income actually rises is no longer the same as the calendar arithmetic of the notice.
• Rent increase strategy has changed. Pre-RRA, modest annual increases were a sensible default. Post-RRA, the rational approach for landlords is to wait until a meaningful gap to market opens, then increase decisively to that market rate — accepting the Tribunal challenge risk and the delay cost as a one-time event rather than an annual occurrence. Frequent small increases produce frequent challenges and frequent delays.

The government has reserved the power to introduce regulations allowing backdating to the original notice date if Tribunal volumes become unmanageable. That backstop is not currently in effect, and landlord planning should not assume it.

Discrimination and advertising rules: an enforcement layer over everything

One element of the Renters' Rights Act has already been in force since 27 December 2025, before Phase 1 commencement: the discrimination provisions in chapter 3 of part 1. Landlords cannot refuse to let to a prospective tenant because they have children or receive welfare benefits. Discriminatory advertising — phrases like "no DSS", "professionals only", "no children" — is itself an offence carrying civil penalties.

This matters in the context of rent rules because the bidding wars ban and the advance rent cap together change how landlords screen for tenant credit risk. Where the legal screens (income, references, guarantor) replace the financial screens (advance rent, bidding), landlords need to be sure those legal screens are themselves discrimination-compliant.

Affordability assessments remain permitted — the Act explicitly preserves the right to consider whether a tenant can afford the rent. What is not permitted is a blanket refusal based on benefits status or family composition. The line between "this tenant cannot afford this rent" (acceptable) and "I do not let to benefits recipients" (not acceptable) is the line the new framework requires landlords to walk carefully.

Common mistakes to avoid

Listing without an asking rent. Online listings, social media posts, agency window cards, and printed brochures all count as written advertising. "POA" and "Contact agent for rent" are no longer acceptable.

Inviting "best offers" once interest is shown. The bidding wars ban applies even where the bidding behaviour comes from prospective tenants competing for a desirable property. Letting agents who tell competing applicants "the highest offer wins" are committing the breach on behalf of the landlord.

Demanding advance rent before signing. The cap applies after signing, but pre-signing demands for any rent (beyond a one-week holding deposit under the Tenant Fees Act 2019) are prohibited. Some landlords still routinely ask for "first month's rent and deposit before contract" — this is now unlawful.

Serving Section 13 too soon. The twelve-month rule is strict. A notice served eleven months after the previous increase, even if the relevant date is more than twelve months out, is invalid. The clock measures from increase date to increase date.

Using the old Form 4 after 1 May. Form 4A is the prescribed form from 1 May 2026. A Section 13 notice on the wrong form is invalid; the landlord must wait twelve months from the (failed) notice attempt to try again, unless the increase predates the change.

Pricing the proposed increase optimistically. Pre-RRA, an aggressive Section 13 figure was rational — the Tribunal could go higher anyway, and most tenants didn't challenge. Post-RRA, it is the landlord's ceiling. Pricing slightly above realistic market rate is now a strategic mistake; the Tribunal will only reduce.

When to get proper legal advice

The Section 13 procedure is straightforward enough that most landlords manage it themselves. Specialist advice is worth the cost where:

• The proposed increase is significantly above what local comparables support, and the tenant has indicated they will challenge.
• You have a portfolio with multiple Section 13 notices pending and need to think about the timing strategy across the portfolio.
• Your tenancy includes contractual rent in advance arrangements that you are unsure about post-1 May.
• You have received complaints or enforcement contact from a local authority about advertising or bidding-related conduct.
• You are a letting agent advising landlords through the transition and need certainty on the conduct rules for staff.

The Law Society's Find a Solicitor service allows you to filter for landlord and tenant specialists by region.

Related guides

• Renters' Rights Act 2025: Complete landlord guide — the parent hub.
• Section 21 abolition and the new Section 8 framework
• From 1 May 2026: end of fixed-term tenancies
• Section 13 procedural guide — Form 4A in detail
• RRA-compliant tenancy agreement template
• Lodger agreements — outside the RRA framework

Sources

• Renters' Rights Act 2025 — full text on legislation.gov.uk
• Section 6 (Section 13 amendments and tribunal powers)
• Housing Act 1988 (the underlying statute as amended)
• Renters' Rights Act Information Sheet 2026 (gov.uk)
• Civil Penalties Guidance (gov.uk)
• Form 4A — Section 13 Notice (gov.uk)
• First-tier Tribunal (Property Chamber) — gov.uk

This guide reflects the position as of 1 May 2026. Secondary legislation under the Act continues to be laid; landlords should check gov.uk for any updates after this date.