Zack Polanski proposes three-year cap on private rent rises

Zack Polanski is expected to call for a three-year cap on private rent increases at the Green Party conference in Brighton on Friday, 2 October. The proposed limit would hold rises to the lowest of consumer price inflation, wage growth or 2%, according to the BBC and Inside Housing. It is a Green Party proposal, not a rule that landlords must currently follow.

The Green leader has described the measure as an emergency brake intended to give tenants breathing space. The two reports were published before his scheduled speech, so the proposal’s details rest on their accounts of what he was expected to announce. Neither report establishes that the speech has since been delivered or that a full policy document has been published.

How Polanski’s three-year rent cap would work

Under the reported formula, the ceiling on an increase would follow whichever of three figures is lowest at the relevant time: the consumer price index measure of inflation, wage growth or 2%. That means the 2% figure is an upper limit within the formula, rather than a guaranteed increase. If either inflation or wage growth were lower, that lower figure would set the proposed ceiling.

The cap is described as lasting three years. Polanski’s stated aim is to slow increases while ministers develop what he calls a national Fair Rents Guarantee for the longer term. He argues that rents have risen beyond wages and that tenants need more certainty about the cost of keeping their homes.

What the latest UK rent figures show

The Office for National Statistics estimated that the average UK private rent was £1,400 a month in August 2026, £52 or 3.8% higher than a year earlier. Annual growth had been 3.7% in July. The ONS said August’s rate was the highest since December 2025, while warning that its latest UK estimates are provisional and may be revised.

The national average also masks regional differences. In England, annual private rent inflation reached 5.8% in both the North East and North West in the year to August, according to the ONS. The South East recorded the lowest English regional rate, at 3.0%. These are measures of observed rent growth, not estimates of what Polanski’s proposal would save any particular tenant.

The ONS says its Price Index of Private Rents covers new and existing tenancies. Its UK estimates for the latest two months are provisional, and Northern Ireland figures for those months include estimates. The agency also advises caution when comparing Scotland and Northern Ireland with other UK countries because their rent data are collected differently.

Inside Housing reports that nearly one in five UK households rent privately. That helps explain the proposal’s potential reach, although neither the size of any saving nor the number of households that would benefit has been established. A cap on increases would also leave open questions about rents charged when homes are newly let and about how landlords might respond.

How the proposal differs from current law

The Renters’ Rights Act has changed rules affecting private tenants, including a ban on no-fault evictions, Inside Housing reports. The BBC says the Act permits landlords to raise rent once a year to the property’s open market rate. Polanski’s proposal would add a separate limit on the size of rises; it should not be confused with a measure already in force.

Inside Housing reports that Labour has ruled out rent controls. Green MP Carla Denyer backed the proposed emergency brake, saying it would provide a reset while a longer-term system of rent controls was developed. Her support is a political argument for the plan, not evidence that the proposed ceiling would produce a particular outcome.

The trade-off for tenants and rental supply

The Institute for Fiscal Studies says rent controls can reduce costs and uncertainty for tenants whose homes are covered. Its assessment also identifies possible costs: fewer homes available to rent, weaker incentives to maintain properties and greater difficulty for some households trying to find suitable accommodation. Those are potential effects of rent controls, not observed effects of this three-year proposal.

The IFS says the effects depend on the policy’s design and the housing market in which it operates. It draws on research from other countries and says direct UK evidence on the effects of rent controls is not yet available. It also suggests temporary controls may carry fewer adverse effects than permanent ones, while offering help for a shorter period.

For renters, the immediate point is therefore limited: Polanski is expected to set out a proposed ceiling for future increases, but no new cap takes effect simply because he announces it. The speech and any subsequent policy text may clarify the unresolved mechanics. Until then, the reported formula defines the Greens’ proposal, while its practical effect remains untested.