Three London councils took the Mayor to the High Court over affordable housing targets. Seven boroughs are behind the claim.

Tower Hamlets, Hackney and Lewisham councils filed a judicial review application at the High Court on 24 June 2026, challenging Mayor Sadiq Khan's decision to reduce London's affordable housing requirement from 35% to 20%. Four further boroughs are supporting the claim. For residential developers with London schemes in planning, the legal outcome will determine whether the 20% fast-track route remains sound.

What happened

In October 2025, the Mayor of London and Housing Secretary Steve Reed jointly agreed to reduce London's affordable housing quota from 35% to 20% as an emergency intervention. The stated objective was to unblock stalled sites, incentivise developers, and accelerate planning approvals in a market where housebuilding had fallen sharply. Schemes committing to 20% affordable provision would qualify for a fast-track planning application; those starting before 2030 would also receive temporary relief from the Community Infrastructure Levy.

On 24 June 2026, Tower Hamlets, Hackney and Lewisham applied for judicial review of that decision. The three councils allege that Khan reduced the quota without using the statutory process required to amend the London Plan, without adequate consultation with boroughs, and without evidence to justify a blanket reduction across all 33 local authorities. Lambeth, Southwark, Waltham Forest and Haringey have formally backed the claim, bringing the total to seven boroughs.

City Hall has defended the decision on viability grounds. The figures behind the policy are significant: just 3,991 affordable homes were delivered in London in 2024-25, against an estimated annual need of 88,000.

Why it matters for developers

Any London mixed-tenure scheme that has secured, or is currently seeking, planning permission on the basis of the 20% affordable requirement is now exposed to legal uncertainty. If the judicial review succeeds and the original London Plan policy is reinstated, schemes that relied on the fast-track route face questions about the basis on which they were approved.

The immediate practical question is documentation. A developer's position in any subsequent dispute rests on the document trail: the planning consent, the section 106 agreement, any heads of terms with the registered provider, and the affordable tenure schedule agreed for the site. For housing associations building their London acquisition pipeline on the assumption of 20% commitments from developers, the uncertainty applies equally: what has been committed, on what terms, and traceable to which signed document?

That is not a due-diligence refinement. For any scheme where affordable housing obligations are in question, the evidential starting point is the document trail from planning permission through to contract, and it needs to be immediately accessible.

What to watch

The High Court has not yet listed a hearing date. City Hall is likely to seek swift resolution: prolonged legal uncertainty will freeze decision-making on schemes in pre-application and planning across the capital. Whether additional boroughs join the claim, and whether central government intervenes in support of the current policy, will shape the timeline. Developers with sites in any of the seven supporting boroughs should expect heightened scrutiny of affordable provision at planning committee.

How Guided Home helps

Section 106 agreements and their associated affordable tenure schedules are legal commitments that need to be traceable throughout a scheme's delivery life. Guided Home's document management platform gives developers and registered providers a single, organised record of planning obligations, tenure agreements, and handover documentation for every scheme, so that the basis of any affordable housing commitment is immediately accessible if it needs to be verified.

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Sources

• Inside Housing — "Three London councils launch legal challenge against mayor's decision to cut affordable housing targets" (24 June 2026)
• Housing Today — "Three London councils launch legal challenge to Khan's cut to affordable housing quota" (24 June 2026)
• The Developer — "London councils launch legal challenge against Mayor over affordable housing targets" (24 June 2026)
• Building — "Three London councils launch legal challenge to Khan's cut to affordable housing quota" (24 June 2026)
• Construction Management — "Three London councils sue Sadiq Khan over affordable housing quota cut" (24 June 2026)
• Hackney Citizen — "Hackney mayor takes Sadiq Khan to court over slashed affordable homes target" (24 June 2026)