Is a licence from another state valid in Western Australia?

Not automatically. Licensing is administered state by state and there is no national register. Mutual recognition schemes exist and can let a licence holder apply to be recognised in another jurisdiction, but that is an application the tradesperson has to have made — it is not automatic, and the register for Western Australia is what settles it.

What percentage of WA businesses publish an ABN you can check?

7.2% of the 3,998 WA businesses in this directory, against 9.8% nationally.

Does an unlicensed tradesperson have to fix bad work?

Consumer guarantees under the Australian Consumer Law apply regardless of whether the tradesperson is licensed — an unlicensed operator cannot escape them by being unlicensed. Enforcing them is another matter, which is why the licence check is worth the minute it takes. If it has already gone wrong, see the guide on what to do when work goes wrong in Western Australia.

Check a tradie licence in WA

Short answer

In Western Australia, licences are issued and published by Building and Energy, covering builders, electricians, plumbers and gas fitters. Search the licence number the business gives you on that register before work starts — it is free and takes about a minute. There is no national licence register in Australia, so a licence from another state does not automatically apply to work done in Western Australia.

Licensing in Australia is a state matter. There is no national register, no single number to look up, and a licence issued in one state does not automatically authorise work in another. In Western Australia, the authority is Building and Energy.

Which register to search in Western Australia

Building and Energy covers builders, electricians, plumbers and gas fitters.

Building and Energy licenses builders, electricians, plumbers and gas fitters, and publishes searchable registers. Gas fitting is licensed separately from plumbing in WA as elsewhere, and it is the distinction most worth confirming before gas work starts.

What to actually look at when the register returns a result

That the licence is current, not expired or suspended. An expired licence is the single most common problem a check finds.
That the name on the licence matches the name on your quote. A licence held by a related company is not a licence held by the business you are contracting with, and it is the contracting entity that owes you the work.
That the licence class covers this job. A general building licence is not an electrical licence, and a plumbing licence does not automatically include gas fitting.
Any conditions on the licence. Conditions exist for a reason and are published where the register shows them.

What 3,998 WA businesses publish about themselves

A licence is not the only thing you can check from outside a business, and the rest is not encouraging. Across every WA business in this directory:

What we checked	WA	Australia
Publish an ABN we could confirm	7.2%	9.8%
Listed phone matches their own website	38.4%	39.2%
Listed phone contradicts their own website	5%	4.8%
Website responded when we checked	64.7%	64.7%
Median Google reviews	30	29

3,710 WA businesses — 92.8% of them — publish no ABN anywhere a customer can find it. An ABN is free to obtain and free to publish, so this is not evidence of anything improper. It does mean the cheapest identity check available to you is unavailable for most of the market, and that asking is reasonable.

What a licence check does not tell you

Whether the work will be any good. A licence is a floor, not a rating.
Whether they carry insurance. That is a separate question with a separate answer, and you should ask it.
Whether the licensed person will be the one on site. Ask who is actually doing the work and whether they are supervised.
Whether they are solvent. A licence stays current right up until a business stops trading.

Common questions

Who licenses tradespeople in Western Australia?: Building and Energy, covering builders, electricians, plumbers and gas fitters. Building and Energy licenses builders, electricians, plumbers and gas fitters, and publishes searchable registers. Gas fitting is licensed separately from plumbing in WA as elsewhere, and it is the distinction most worth confirming before gas work starts.
Is a licence from another state valid in Western Australia?: Not automatically. Licensing is administered state by state and there is no national register. Mutual recognition schemes exist and can let a licence holder apply to be recognised in another jurisdiction, but that is an application the tradesperson has to have made — it is not automatic, and the register for Western Australia is what settles it.
What percentage of WA businesses publish an ABN you can check?: 7.2% of the 3,998 WA businesses in this directory, against 9.8% nationally.
Does an unlicensed tradesperson have to fix bad work?: Consumer guarantees under the Australian Consumer Law apply regardless of whether the tradesperson is licensed — an unlicensed operator cannot escape them by being unlicensed. Enforcing them is another matter, which is why the licence check is worth the minute it takes. If it has already gone wrong, see the guide on what to do when work goes wrong in Western Australia.

How to check a tradesperson's licence in Western Australia