The building safety levy, and the brownfield discount

The building safety levy comes into operation in England on 1 October 2026. It is charged on building control applications submitted on or after that date, where the work creates new dwellings, creates new bedspaces in purpose-built student accommodation, or changes the use of a building to residential. Applications submitted before the date are outside it. That gives a little over two months, and the date is fixed rather than indicative.

What is charged, and by whom

The levy is a charge per square metre of chargeable floorspace. The rates are set nationally but differ by local authority area, weighted using average house prices so that the areas with the highest prices carry the highest rates. The full table sits in Schedule 3 of the government's guidance.

Local authorities collect it, on the basis that they already hold the building control process and know how to collect a tax. Payment falls due before completion or occupation of the building, whichever comes first, which means the liability lands at the end of a project rather than the start of it.

A major residential development, for the purposes of the levy, is one producing at least 10 new dwellings or at least 30 student bedspaces. Below that, smaller developments are treated differently.

What is not charged

The exemptions are broad and worth reading properly rather than assuming. Affordable housing at social and affordable rent, shared ownership, and First Homes meeting the stated conditions are outside the levy. So is supported housing provided by a local authority, housing association, charity or voluntary organisation, and anything built by a non-profit registered provider of social housing or its wholly-owned subsidiary. A list of building types is also excluded, among them schools, hospitals, care homes, prisons, almshouses and hotels.

The discount that turns on the land

The part most likely to be argued over is the previously developed land rate. A development built on previously developed land is charged at half the standard rate, in recognition that building on that kind of land usually costs more.

The definition is precise. For levy purposes, previously developed land is land which either has a building on it now, or had a building on it at any point on or after 1 July 1948. And to qualify as a previously developed site, at least 75% of the land inside the redline boundary of the development, as specified by the planning permission, has to meet that definition.

Read that again as a records question rather than a policy one. The discount does not depend on the building you are about to put up. It depends on two facts about the ground: what stood there historically, and what proportion of the consented site that covers. On a site of any real size, half the levy is a substantial sum, and it is decided by a boundary and a history.

The evidence is usually scattered

The awkward part is not the test, it is proving it. Meeting the 75% threshold means being able to show the redline boundary exactly as consented, the historic footprint of whatever stood on the site, and an area calculation that ties the two together. In practice that evidence lives in several places at once: a boundary plan with the solicitor, historic mapping inside a consultant's desk study from three years ago, planning history in a folder named after whoever compiled it, and a site plan that may or may not be the version that was approved.

None of it is hard to produce. It is just rarely in one place, and it tends to be assembled under time pressure, at the point where a payment is already due.

Keeping it together is ordinary discipline. The land boundaries record holds the redline as drawn and consented rather than as remembered. The planning register keeps the consents and their conditions against the site they belong to. The wider land and site record carries what is known about the ground itself, and documents holds the surveys and desk studies that evidence it, versioned and dated, so the report being relied on is the current one.

Two months

For anyone with development coming forward, the practical questions are narrow. Which applications will land after 1 October. Which sites would meet the 75% test. And could you show it today, from records you already hold, if a collecting authority asked.

The first two are answerable from a programme. The third is answerable from a site record, or it is not.