Owning the tree is not the test
The common assumption is that if your tree damages a neighbour's property, you pay. That is not how it works in Australian law.
Liability generally arises in negligence, and negligence requires a failure to take reasonable care. The question is whether you knew, or ought reasonably to have known, that the tree presented a foreseeable risk, and whether you did anything about it.
A structurally sound tree brought down by an exceptional storm is usually treated as an act of nature. Each party claims on their own insurance and nobody is liable to anybody.
A tree that was visibly dead, had fungal brackets at the base, had been the subject of a written complaint, or had already dropped a limb, is in a different category entirely.
What "ought to have known" means in practice
You are not expected to be an arborist. You are expected to notice the obvious and to respond to what you are told.
Things that put an owner on notice: a dead or largely bare crown, fungal brackets or conks on the trunk or at the base, a visible cavity or major crack, a new or increasing lean, lifted soil at the base, a previous limb failure, and — most powerfully — a written notice from a neighbour or a council.
Once any of those exists, the reasonable step is to get a qualified arborist to assess the tree and to act on the advice. Doing that and keeping the report is a strong position even if the tree later fails.
Written notice cuts both ways
If you are the concerned neighbour, put it in writing. A polite letter or email describing what you have observed, dated, with photographs. Keep a copy. That single document is what establishes knowledge.
If you are the tree owner and you receive one, do not ignore it. Get the tree assessed. A few hundred dollars for a written assessment is inexpensive compared with the alternative, and if the arborist says the tree is sound, you now have a professional opinion on file.
Overhanging branches
At common law you may generally cut back to the boundary line, at your own expense, without entering the neighbour's property. The cuttings remain the tree owner's property — returning them over the fence is traditional but is not always well received.
The limits matter more than the right. If the tree is protected under Central Coast Council's provisions, you need approval like anyone else. If you prune so heavily that the tree is damaged, destabilised or killed, you can be liable for that. And a heavy one-sided prune on a boundary eucalypt can genuinely make it more dangerous, not less.
Talk first. It is cheaper than every alternative.
Roots
Same principle, harder to see. Roots lifting your paving or blocking your pipes are damage, but gradual damage is a standard insurance exclusion and the negligence test still applies. Cutting structural roots on a boundary tree can destabilise it, at which point responsibility for the failure may shift towards you.
Get advice before a root barrier or a trench goes in near a large boundary tree.
The formal pathway
Where negotiation fails, the Trees (Disputes Between Neighbours) Act 2006 provides a route to the NSW Land and Environment Court. It covers trees causing or likely to cause damage or injury, and in specified circumstances hedges obstructing sunlight or views. It is not a quick process and it is worth legal advice first.
Doing it properly
Get the trees near your boundary assessed while everyone is on speaking terms. The signs a tree needs removing article covers the defects that matter, the approval guide covers the permit side, and the home insurance guide covers who pays for what.
Frequently asked questions
My tree fell on my neighbour's fence. Do I have to pay?
Not automatically. Liability in negligence generally requires that you knew or ought reasonably to have known the tree was dangerous and failed to take reasonable steps. A healthy tree brought down by an extreme storm is usually treated as an act of nature and each party claims on their own insurance. A visibly dead tree that a neighbour had raised with you in writing is a very different position.
Does written notice from a neighbour change my position?
Significantly. A written notice that a tree appears dead, damaged or dangerous puts you on notice, and from that point the question of whether you ought to have known is largely answered. Ignoring it is the single most effective way to convert a natural event into a negligence claim. Get the tree assessed by a qualified arborist and keep the report.
Can I cut branches that hang over my fence?
At common law you may generally prune back to the boundary at your own cost, without entering the neighbour's land, and the cuttings remain their property. The right is limited. It does not apply where the tree is protected under Central Coast Council's vegetation provisions, and pruning so heavily that you damage or kill the tree exposes you to a claim. Check protection status first.
What if talking to the neighbour does not work?
The Trees (Disputes Between Neighbours) Act 2006 allows an application to the NSW Land and Environment Court for orders where a tree is causing or is likely to cause damage to property or injury to a person, and in defined circumstances where a hedge severely obstructs sunlight or a view. It is a formal process. Get legal advice before starting it.