A SHLAA is a council writing down which land in its district it thinks could take housing, how many homes, and when. It is the closest thing to a planning officer’s own shortlist, it is public, and most people sourcing land never open one.
This post covers what is in an assessment, what the decision statuses actually mean, and how to use one without over-reading it.
What a SHLAA is, and what it is called now
The name has drifted. Many councils still publish a Strategic Housing Land Availability Assessment; others publish a Housing and Economic Land Availability Assessment, or HELAA, which is the term used in Planning Practice Guidance (last updated 27 November 2025). The National Planning Policy Framework published on 17 August 2026 calls it simply a land availability assessment, under policy PM9.
All three mean the same evidence base. It is a plan-making requirement in England: development plans should be informed by an assessment of the land available in the area to meet development needs, and plans that allocate specific sites have to do it in more detail. Policy HO3 then requires the local plan to identify a supply of sites drawing on that assessment.
It is not a statutory register and it is not a promise. PPG is explicit that the assessment does not in itself determine whether a site should be allocated — that is for the plan.
What the assessment has to establish
Under policy PM9, an assessment that supports site allocations should include:
- a thorough site identification process, producing a sufficient range and quantity of sites;
- an assessment of the availability, suitability and achievability — including likely viability — of each;
- an assessment of how much development each site could take, and over what timescale;
- the identification of appropriate sites, against the plan’s emerging spatial strategy.
Availability, suitability and achievability are the three questions. A site can fail on any one of them, and the stated reason is usually the most useful sentence in the whole document.
How sites get into a SHLAA
- Call for sites. The council invites landowners, promoters and agents to submit land. This is the main intake, and it is also a public list of owners who have told the council they would sell or promote;
- Other sources. Previous assessments, existing allocations, sites with permission, and the council’s own capacity studies;
- Assessment. Each site is tested against size thresholds, access, infrastructure, policy fit and environmental or heritage constraints;
- Publication. The assessment is published and refreshed periodically — typically annually, and at minimum when the plan is reviewed.
Reading the decision status
Most assessments classify sites as deliverable, developable, or neither. Those terms are defined in the NPPF glossary and they are about timing and certainty, not merit.
- Deliverable — available now, a suitable location for development now, and with a realistic prospect that housing will be delivered within five years. These feed the five year supply;
- Developable — in a suitable location with a reasonable prospect of coming forward in years six to ten or beyond;
- Not developable — with a stated reason. Read the reason. “No safe access” is a dead end; “outside the settlement boundary” is a policy position that can change when the boundary or the council’s housing position does.
Each entry typically also carries the site name and location, an estimated capacity in units, and an indicative timeframe.
Why it is worth the read
A SHLAA gives you three things you would otherwise pay for. It tells you which land the council has already accepted is suitable in principle. It tells you which landowners have raised their hand. And where a site was rejected, it tells you precisely what would have to change.
That last one is where the money is. A site marked not developable on housing land supply grounds in a district that has since lost its five year supply — or fallen below 75% on the Housing Delivery Test — is a different site to the one that was assessed.
The same applies to sites rejected for being outside the line. Read them against what national policy now allows outside a settlement boundary, which is a longer list than it was.
Getting hold of the data
Every authority publishes its assessment, and every authority publishes it differently — PDF appendices, spreadsheets, occasionally a map. Site references rarely match between rounds, and capacity figures get restated without being flagged.
BOOM! carries SHLAA sites as a mapped data layer with a filter panel, so you can see assessed sites against ownership, planning history and constraints instead of reconciling documents by hand.
What a SHLAA does not tell you
Inclusion is not allocation, and allocation is not permission. A site can sit in an assessment for a decade. Treat it as evidence of what the council thinks, dated to when it thought it — always check the base date — and pair it with the district’s current housing supply position before you act on it.
