NPTC, BS 3998 and ARB Approved: What Tree Surgery Qualifications and Insurance Actually Mean

Four credentials appear on almost every tree surgery website in the UK: NPTC, BS 3998, ARB Approved Contractor, and a public liability figure. They are not four versions of the same thing. One is an assessed qualification held by an individual. One is a published standard with no certificate attached. One is an independent audit of a business. One is an insurance policy.

Knowing which is which tells a homeowner exactly how much weight each badge carries.

There is no such thing as a licensed tree surgeon

Tree surgery is not a regulated profession in the United Kingdom. No register must be joined, no examination must be passed, and no licence can be revoked. The word "licensed" on a tree surgery website normally refers to a waste carrier registration, which is a permit to transport waste and says nothing about competence with a saw.

What the law does require is narrower and more specific. Under the Provision and Use of Work Equipment Regulations 1998, anyone operating a chainsaw at work must have received adequate training and be competent for the particular task. The Health and Safety Executive treats a recognised certificate of competence as the normal evidence of that. Competence is therefore assessed task by task, not once for the trade as a whole.

Winchester City Council's position reflects this. The council states it cannot advise private tree owners on the safety of their tree or what work it needs, and directs owners instead to the Arboricultural Association's find-a-professional directory. The local authority that administers Tree Preservation Orders across the district does not itself vouch for any contractor. Verification sits with the homeowner.

NPTC certificates of competence: unit by unit

NPTC, now part of City & Guilds, issues certificates of competence in individual chainsaw and arboricultural operations. Each unit is separately trained and separately assessed. The units that matter on domestic tree work are:

Unit	What it certifies
CS30	Chainsaw maintenance and cross-cutting
CS31	Felling small trees
CS32	Felling medium trees
CS34	Dealing with windblown trees
CS38	Climbing a tree and performing an aerial rescue
CS39	Using a chainsaw from a rope and harness
CS40	Aerial tree pruning
CS41	Aerial cutting of trees using free-fall techniques (rigging and sectional dismantling)
CS47	Using a chainsaw from a mobile elevating work platform

The practical point is the gap between units. An operative holding CS30 and CS31 is certified for ground-based cutting and felling small trees. That person is not certified to climb, to cut from a rope and harness, or to dismantle a large tree in sections above a building. Lantra Awards issues equivalent qualifications covering the same operations.

Ask which units the person actually climbing your tree holds, not which units the company collectively holds. On a large removal requiring rigging over a structure, CS38, CS39 and CS41 are the relevant ones, the same competences that make sectional dismantling of a large tree beside a house a controlled operation rather than a gamble.

Aerial work brings a second requirement. Climbing harnesses, ropes, karabiners and lowering equipment are lifting equipment used to lift a person, so the Lifting Operations and Lifting Equipment Regulations 1998 require thorough examination at least every six months by a competent person. Ask when the kit was last examined.

BS 3998:2010 is a standard, not a certificate

BS 3998:2010 Tree work, Recommendations is the British Standard covering when tree work should be carried out, how it should be specified, how it should be executed, site management, and the treatment of veteran trees and wildlife habitat.

No one is certified in BS 3998. There is no examination, no assessor and no certificate. A company stating BS 3998 compliance is making a declaration about its working practice. The declaration is meaningful only if the specification it produces reflects the standard.

Two things in a written quote show whether it does. The standard advises against removing a large proportion of a mature crown in one operation, so a specification proposing a modest percentage reduction with cuts to suitable growth points is consistent with it, and a proposal to reduce a mature tree by half is not. The standard also treats topping, cutting main stems back to stubs, as poor practice on amenity trees. A quote that specifies topping is not BS 3998 work regardless of the logo on the letterhead.

ARB Approved Contractor: the badge that assesses the business

The Arboricultural Association's ARB Approved Contractor scheme is the only one of these four credentials that independently assesses the company. Approval covers the quality of tree work, health and safety procedures, business practice and customer care, and is subject to reassessment rather than being awarded permanently.

Two related but different accreditations exist. ARB Approved Contractor applies to contracting businesses carrying out tree work. Registered Consultant status applies to consultants producing reports and surveys. Individual arborists may separately hold ISA Certified Arborist status from the International Society of Arboriculture, which assesses the person's knowledge rather than the firm's systems.

A contractor without ARB Approved status is not thereby unqualified, the scheme carries an assessment cost and an administrative burden that many competent small firms do not take on. It shifts where the burden of proof sits. Without it, the individual certificate and insurance checks matter more, which is the reasoning behind the nine questions to put to a tree surgeon before hiring and the order they are best asked in.

Employers' liability and public liability are not the same obligation

Employers' liability insurance is compulsory. The Employers' Liability (Compulsory Insurance) Act 1969 requires any business with employees to hold at least £5m of cover. It pays when an employee is injured. Trading without it is an offence.

Public liability insurance is not compulsory. No statute requires a tree surgery business to hold it. It pays when the business injures a third party or damages third-party property, the neighbour's greenhouse, the parked car, the boundary wall. UK arboricultural practice treats £5m as the working minimum and £10m as standard for work near highways.

Three checks on the certificate matter more than the headline figure:

• Expiry date. A certificate from a previous policy year proves nothing about today.
• Described activities. The policy schedule must include tree work at height and chainsaw use from a rope and harness. Some policies written for general landscaping exclude both.
• Named insured. The company name on the certificate should match the company name on the quote and the invoice.

Damage caused by an uninsured contractor becomes a civil claim against a business that, in the cases where this goes wrong, has no assets and often no continuing existence.

Waste carrier registration and the paperwork it should generate

A business transporting waste produced by others must register with the Environment Agency as an upper tier waste carrier. Registration lasts three years and is publicly searchable by name or registration number.

This registration protects the homeowner directly. A householder has a legal duty of care to pass waste only to an authorised carrier, and a fixed penalty of up to £600 can be issued to the householder where waste is later fly-tipped and no reasonable check was made. Requesting the registration number and keeping the invoice is the whole of the required check.

Verifying all of it independently

Each credential has an independent verification route. None requires more than a few minutes.

• NPTC units, ask for certificate copies showing the holder's name and unit numbers, then confirm the named individual is on site.
• ARB Approved Contractor, search the Arboricultural Association's directory at trees.org.uk by postcode and confirm the approval is current.
• ISA Certified Arborist, verify the individual through the ISA's own register.
• Waste carrier registration, search the Environment Agency's public register of waste carriers, brokers and dealers.
• Insurance, request the certificate directly and, where the value of the property at risk justifies it, contact the named insurer to confirm the policy is live.
• BS 3998, unverifiable by register. Judge it from the written specification.

A contractor unwilling to supply the documents for these checks has answered the question. Details of the qualifications, insurance and registrations held by our own team, and the units each climber works under, are set out on our team and accreditation page, and we send certificates by email before quoting rather than waiting to be asked.