Do arborists need professional liability (E&O) insurance?

Professional liability insurance — also called errors and omissions (E&O) insurance — covers claims arising from professional negligence: mistakes, oversights, or faulty advice in the delivery of professional services. For arborists, this is a fundamentally different exposure than the bodily injury and property damage covered by general liability, and it requires a separate policy.

General liability covers what you physically do — a branch falls on a car, a crew member damages a fence, a pedestrian trips over equipment. Professional liability covers what you know and recommend — your expert judgment. When an ISA Certified Arborist performs a tree risk assessment and rates a tree as low risk, and that tree subsequently fails and damages a home, the homeowner's claim is not that the arborist caused physical damage (GL) but that the arborist's professional assessment was negligent (E&O). The CGL policy specifically excludes professional services, so without E&O coverage, this claim is uninsured.

Common professional liability claims against arborists include incorrect tree risk assessments (tree rated safe subsequently fails), misidentification of disease or pest infestations leading to tree loss or spread, improper treatment recommendations that damage or kill trees, failure to identify protected species before removal (resulting in regulatory fines and restoration costs), negligent preservation plans during construction that result in tree decline or death, and expert witness testimony that is challenged or discredited.

Professional liability policies for arborists are typically written on a claims-made basis, meaning the policy must be in force both when the alleged negligent act occurred and when the claim is reported. This introduces the retroactive date and tail coverage considerations discussed elsewhere. The claims-made structure reflects the fact that professional negligence claims often surface years after the work — a tree risk assessment performed today might not be questioned until the tree fails five years from now.

The American Society of Consulting Arborists (ASCA) recommends that all consulting arborists carry professional liability insurance, and ISA standards of practice create a duty of care that elevates the professional negligence exposure for certified arborists. TCIA member companies that offer consulting services should also carry E&O coverage. Premiums depend on revenue from consulting services, the types of services offered (risk assessments carry higher exposure than routine pruning recommendations), claims history, and the coverage limits selected. Most arborists carry $1 million per claim / $1 million aggregate E&O limits.

If your tree service offers any consulting, diagnostic, or advisory services — even informally as part of maintenance contracts — discuss professional liability coverage with your broker. The line between 'operational' work covered by GL and 'professional' advice covered by E&O is often unclear in practice, and having both policies ensures no gap exists.