Martyn's Law: working out which of your buildings is in scope

The Terrorism (Protection of Premises) Act 2025 — Martyn's Law — is expected to come into force in spring 2027, with the SIA as regulator. For a facilities team the first job is not compliance. It is scoping: which buildings are in, and at which tier.

That sounds administrative and is not, because most estates do not hold the figure the test depends on.

The two tiers, and where the line falls

• –Standard tier: premises where it is reasonable to expect 200 to 799 individuals — staff included — to be present at the same time.
• –Enhanced tier: 800 or more, on the same counting basis. Qualifying events of 800 or more with controlled entry are treated the same way.
• –Childcare, primary, secondary and further education premises, and places of worship, stay in the standard tier even above 800. Higher education does not get that exception.

Staff counting towards the figure is the detail most people miss on a first read, and it is the one that moves borderline premises across the line.

Why the headcount is the hard part

The test is how many individuals it is reasonable to expect to be present at the same time, staff included. Not the fire capacity. Not the lettable area. Not the number on the licence.

An asset register records plant. A compliance register records inspections. Neither usually records how many people are in a building at once, and on a mixed estate the answer varies by day of the week and by what is booked.

• –A building with 180 desks and a 60-seat event space crosses the line on the days the space is used.
• –A site where a contractor brings forty people on a shutdown is a different building that week.
• –A building counted at its occupancy figure and not its visitor peak will be scoped wrong.
• –Shared buildings raise a question about who the responsible person is at all, which has to be settled in the lease or the management agreement rather than assumed.

So the scoping exercise is a data exercise first: establish, per building, a defensible figure for reasonable maximum simultaneous occupancy, and record how it was arrived at. That record is what will be produced if the tier is ever questioned.

What each tier adds to the estate's workload

• –Standard tier: notify the SIA, and have procedures for evacuation, invacuation, lockdown and communication so far as reasonably practicable. No physical measures required.
• –Enhanced tier: those, plus measures to reduce vulnerability and harm, documented, assessed for effect and sent to the regulator — and a designated senior individual responsible for compliance.

The enhanced tier is the one that creates a recurring obligation rather than a one-off. A document sent to a regulator becomes a document that has to stay true, which means it joins the things with review dates — alongside the statutory inspections a facilities team already runs.

What to do with the time left

• –Produce the occupancy figure per building, with its basis, and get it agreed rather than estimated by one person.
• –Identify the responsible person per building in writing, especially where a building is shared or managed on behalf of somebody else.
• –Check which buildings fall into the education, childcare or place of worship carve-out, which keeps them in the standard tier regardless of size.
• –Find the buildings near the thresholds and decide what would move them, because those are the ones that will be wrong first.
• –Fold the outcome into estate-wide compliance reporting rather than keeping it in a separate spreadsheet, which is how the next duty gets forgotten.

The SIA said it would publish final regulatory guidance with a consultation report in autumn 2026. Read that before building a process around any of this, and check the statutory guidance below for the tier tests rather than relying on a summary.