National Security Inspectorate (NSI)
Independent certification body for security and fire-safety installers.. Last reviewed April 2026 by the TradeMatch editorial team.
National Security Inspectorate (NSI) is a UK accreditation body covering security systems. Independent certification body for security and fire-safety installers. For UK homeowners, an NSI-registered tradesperson signals that the firm has been independently vetted for technical competence, insurance cover and adherence to a written code of conduct. Verification is free at the body's public register: www.nsi.org.uk.
Visit Official Register ↗
What does NSI cover?
NSI accreditation typically covers technical competence, ongoing CPD requirements, insurance cover (typically £2M+ public liability) and a published code of conduct. Each NSI member is required to renew or be reassessed periodically — the exact cadence depends on the membership tier. The body operates a complaints route for homeowners: if a registered member fails to honour their commitments, NSI can investigate, mediate, and in serious cases revoke membership.
Verifying a NSI-registered tradesperson
- NSI membership number — verify on the public register before signing any quote
- Current insurance certificate (£2M+ public liability typical) — NSI requires this for active members
- Written quote with payment milestones — NSI members commit to written contracts, not verbal agreements
NSI applies to these trades
100%of TradeMatch payments held in escrow
Every job, every payment, every time. Funds held in a segregated client account until you sign off the work.
- Held in escrowFrom the moment the deposit clears until the job is signed off.
- Released on sign-offFunds release within 24 hours of you confirming the work is done to spec.
- Disputed = frozenIf something is wrong, the payment freezes pending review by our resolution team.
TradeMatch escrow operates through FCA-regulated payment providers. Customer funds are segregated from operating accounts and protected under UK consumer law.
NSI FAQ
What does NSI accreditation actually require?
Technical competence (typically a recognised qualification), evidence of trading history, current insurance, adherence to NSI's published code of conduct and a documented complaints procedure. Some tiers require independent audit; all require periodic reassessment.
How do I check if a tradesperson is NSI-registered?
Visit https://www.nsi.org.uk/ and use the public register search. Always check before signing a contract — registrations occasionally lapse, and the public register is the authoritative source.
Is NSI membership legally required?
For most trades, no — UK trade accreditation is voluntary. The big exceptions are Gas Safe (legally required for gas work) and some renewable-energy schemes (MCS required for grant claims). For other trades, NSI membership is a strong quality signal but not a legal mandate.
What if I have a problem with an NSI member?
Raise it directly with the trader first, in writing. If unresolved, escalate to NSI via their complaints procedure. NSI can investigate, mediate and ultimately remove members who fail to meet the code. On TradeMatch, escrow-protected payments mean disputes are mediated before any release of funds — a faster route in practice.
Why NSI verification matters before any deposit
Lapsed accreditations are the most common silent failure on UK trade hires — registrations expire annually and not every trader updates their listing. Always verify the NSI number on the public register on the day you sign, not at first meeting. On TradeMatch, every NSI-registered tradesperson is independently re-checked before they can quote on your job, and the registration link is shown on their profile so you can confirm yourself.
Get a NSI-Verified Quote
Up to 5 quotes from UK tradespeople — every NSI-relevant member independently verified by TradeMatch. Escrow-protected payments. Reviews tied to completed jobs only.
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