The two dates every London developer should care about: 1 July and 31 December 2026

Most of the regulatory conversation in London right now is about the 1 July date. That is the date the December 2024 NPPF reforms reach into seven specific boroughs and tilt the planning balance toward the applicant. It is a real change, and it is worth understanding. But the second date, the one buried inside a set of dry-sounding Regulations that came into force in late March, is the one that does the larger structural work. On 31 December 2026, five different London boroughs run out of road on a parallel timeline that has had almost no press coverage at all. The two dates are not the same mechanic, they apply to different boroughs, and they pull in opposite directions. For an applicant sitting in front of a refused application, getting them confused is expensive.

This piece sets out what each date does, names the boroughs each one touches, and reads both against the small-site refusal data Perfect Scale holds across the 33 London boroughs.

1 July 2026: seven boroughs about to tilt

The mechanic, set out in NPPF paragraph 78c, requires a council to apply a 20% buffer to its five-year housing land supply calculation where three conditions are met simultaneously: a housing requirement adopted within the past five years against the pre-December 2024 NPPF, an annual requirement that sits at or below 80% of the standard-method local housing need, and a 20% buffer not already triggered by the 2023 Housing Delivery Test result.

Lichfields’ April 2025 analysis identified the London cohort that lands inside all three filters: Barnet, Bexley, Brent, Merton, Waltham Forest, Wandsworth and Westminster. From 1 July, each of these seven boroughs must demonstrate not the standard five-year supply but five years plus a fifth on top.

Where a council cannot show the required supply, NPPF paragraph 11d engages the tilted balance: the presumption that planning permission should be granted unless the adverse impacts of doing so significantly and demonstrably outweigh the benefits. For sub-10 unit schemes determined under delegation, that shift in the test is what shows up at the margin. A refusal that was comfortably defensible at appeal under a five-year supply position becomes more contestable under a four-and-a-half-year position. The trigger does not force approvals. It raises the cost of refusing, and that cost surfaces most visibly on the borderline scheme.

We covered the seven-borough cohort in more detail in the standalone analysis of the 1 July buffer. The point worth carrying into the second date is that the buffer mechanic applies to boroughs whose plans were adopted within the past five years. The boroughs we look at next are in the opposite position. Their plans are about to age out, or already have, and the regulatory question is not what the buffer does to a settled plan but what happens when a borough fails to settle a new one in time at all.

31 December 2026: five boroughs racing a cliff

On 25 March 2026 the Town and Country Planning (Local Planning) (England) Regulations 2026 came into force. They replace the entire procedural framework for preparing a Local Plan with a new 30-month gateway system, structured around three statutory checkpoints (Gateways 1, 2 and 3) and a digital-first plan format. The roadmap document published by the Ministry on the same day sets out the transition: a council that has submitted a Local Plan under the legacy system by 31 December 2026 can continue to examination and adoption under the old rules; a council that has not must restart under the new regime.

Restart, in this context, is the correct verb. The new system requires a Gateway 1 self-assessment within 30 April 2027 (or, for boroughs with plans still inside their five-year window, by the date the plan turns five, whichever is later). Multiple Regulation 18 and Regulation 19 stages already undertaken under the old regime do not transfer cleanly. The practical effect is typically eighteen to twenty-four months of policy vacuum during which the London Plan (now over five years old) and the standard-method local housing need do the heavy lifting. The tilted balance is the default, not the exception.

Lichfields’ 20 March 2026 piece on the implications for London named the boroughs targeting submission inside the deadline: Bromley, Greenwich, Hammersmith & Fulham, Kingston upon Thames and Sutton. Each of the five is currently at Regulation 18 or Regulation 19 stage, each is publicly committed to submission before the cut-off, and each has roughly seven months of working time to get there.

Two structural points are worth pulling out. The first is that the cliff lands on boroughs whose plans are old, not new. None of these five is in the buffer set. The buffer set protects boroughs with recently adopted plans against the structural-method calculation; the cliff exposes boroughs whose plans are running out to a procedural restart. They are different sides of the same machine. The second is that even a borough that submits on time still has to survive examination under the old regime, which historically takes 18 to 30 months. So the operative period in which the existing plan continues to govern is, in the best case, still bounded.

What the data shows for the five

The Perfect Scale dataset covers 375 small-site (3–10 unit) determinations across these five boroughs in the three-year window to 31 March 2026. Refusal rates, ranked from most permissive to least, look like this:

Borough	Determined	Refusal rate
Greenwich	73	41.1%
Sutton	67	43.3%
Hammersmith & Fulham	84	46.4%
Kingston upon Thames	42	47.6%
Bromley	109	56.9%

For comparison, the London-wide refusal rate on 3–10 unit schemes over the same window is 43.1% on 3,321 determinations. Greenwich and Sutton sit inside that average. Hammersmith & Fulham and Kingston sit modestly above it. Bromley sits 13.8 percentage points above the London average and is the only one of the five whose current refusal posture would itself flag in our quality checks. The combination of being the most refusal-prone of the five and the one with the most at stake on the plan-making timetable is worth pausing on.

The reading is not that a Bromley applicant should wait for the new plan. It is that the existing plan is the operative document for any application going in over the next twelve to eighteen months, the borough’s current refusal posture is what is actually being decided against, and the chance of a meaningful soft landing post-31-December is lower than the soft framing of “targeting submission” suggests. If the borough misses the cut-off, the policy frame moves to standard-method local housing need against a tilted balance, which is a more applicant-favourable position than the current plan. If it makes the cut-off, examination of the submitted plan still takes 18 to 30 months on past form.

What the two dates do together

The cleanest way to read the two together is that they touch twelve of the 33 London boroughs, but they touch them in opposite directions.

The seven 1-July buffer boroughs are protected by a recently adopted plan and now stand to lose some of that protection on the supply calculation. The five 31-December cliff boroughs are exposed by an ageing plan and stand to gain some applicant-favourable cover if they miss the submission deadline. Both shifts, in their different ways, raise the cost of refusing at the margin. Both surface most visibly on the small-site delegated decision, where the case officer’s read of the planning balance does most of the work. And the twelve boroughs cover roughly a third of all small-site determinations in our London dataset over the past three years, so this is not a marginal pocket of the market.

The twenty-one boroughs that fall in neither cohort are, in policy terms, the most stable of the three groups. Their plans have already crossed the five-year line, their supply calculation already runs against standard method, and the tilted balance has been quietly available across most of that cohort since March 2026 anyway. The two dates in this piece are not the only dates that have moved the planning balance in London this year. They are the visible, named, dated versions of a shift that has been working through the system for months.

What to do with this before exchanging

Three concrete things are worth doing before exchange in any of the twelve.

First, read the borough’s most recent Annual Position Statement or 5YHLS update directly. The buffer mechanic and the cliff mechanic both turn on numbers the council publishes once a year, and the published number is the one that determines whether paragraph 11d engages on any given appeal. Reading it second-hand from a planning consultant’s commentary is fine; reading it on the council website is better.

Second, ask the borough’s own planning service the simple procedural question. For a buffer borough: does it currently demonstrate the required 5YHLS plus the 20% buffer, as of the most recent calculation? For a cliff borough: is the borough still on track for 31 December submission, and if it slips, what is the contingency? Both questions are public-record material. Neither is something a buyer should be reading for the first time from the council on the way to committee.

Third, look at the existing refusal posture. The Perfect Scale free dashboards for each of the twelve carry the small-site approval rate, the conservation-area density penalty, and the refusal-reason taxonomy that has actually applied in that borough over the past three years. None of those numbers change overnight on 1 July or 31 December. They are the operative starting point against which the two dates do or do not move the marginal case.

Sources. National Planning Policy Framework, December 2024, paragraph 78c. Lichfields, “The Presumption: a London focus” (8 April 2025), for the seven-borough buffer cohort. Lichfields, “As the London Plan turns five” (20 March 2026), for the five-borough plan-making cohort. Ministry of Housing, Communities and Local Government, “Rollout of the new local plan-making system” (25 March 2026), for the transition deadlines.