Can you write off commercial solar instantly? Usually not — and here is why.
It is the most common line in a commercial solar pitch and it is usually wrong. The instant asset write-off is a per-asset limit of $20,000, not a pool or a total, and a commercial solar system almost always costs a multiple of that. The ATO also publishes no limit at all past 30 June 2026. None of this means solar is a bad investment. It means the tax line in the proposal is doing work it cannot support.
Reviewed by the Mission Green commercial team · Updated August 2026
What the write-off
actually is.
A per-asset limit with a timing test — not a discount on your project.
The instant asset write-off is part of the simplified depreciation rules. An eligible business can immediately deduct the business portion of the cost of an asset in the year the asset is first used or installed ready for use.
The ATO publishes the limits in two tables. For businesses with aggregated turnover under $10 million applying the simplified depreciation rules, the limit is $20,000 for assets first used or installed ready for use between 1 July 2023 and 30 June 2026. A separate table covers businesses with turnover of $10 million or more.
Two features of that rule do most of the damage to the sales pitch. First, the limit is per asset — you can write off multiple assets in a year, but each one must individually cost less than the limit. Second, it is a deduction, not a rebate: it reduces taxable income, so what it is worth to you is the deduction multiplied by your tax rate, not the sticker price of the equipment.
Why commercial solar
usually falls outside it.
The arithmetic is not subtle.
$20,000 per asset
Not a total, not a pool, not an annual allowance. Each individual asset must come in under the limit on its own.
Commercial solar costs more
A commercial rooftop system is generally a multiple of $20,000 installed. On cost alone it sits outside the instant write-off.
Ordinary depreciation
The asset is depreciated over its effective life, or through the small business pool if you use the simplified rules. You still get the deduction — just spread out.
This is why "you can write the whole thing off this year" is a claim worth pausing on. For most commercial solar systems it is not the instant asset write-off doing that work, because the system costs more than the limit.
The deduction has not disappeared. It has simply become ordinary depreciation, which is a materially different cash-flow story from an immediate deduction — and a different one again from the "it pays for itself at tax time" framing that sometimes accompanies it.
The ATO publishes nothing
past 30 June 2026.
If a proposal quotes a limit for this financial year, ask where it comes from.
The ATO's published table runs to 30 June 2026 and stops. For assets first used or installed ready for use from 1 July 2026, the ATO page does not publish a $20,000 limit.
We are not going to tell you what the limit for the current year will turn out to be, because the ATO does not currently publish one and we do not restate figures a primary source has not published. What we will say is that a commercial solar proposal asserting a specific write-off for a system installed in this financial year is asserting something the ATO's own guidance does not presently support. That is a question for your accountant, not for your solar retailer.
The timing test compounds this. The asset must be first used or installed ready for use within the income year. Ordering, paying a deposit or having equipment delivered is not enough. For commercial solar — where grid connection approval can sit between a finished array and a commissioned system — that distinction has real teeth near a year end.
So what should
your business actually do?
Short version.
Judge the system on electricity, not on tax. Commercial solar earns its return by displacing consumption you would otherwise buy at retail rates. If the business case only works once a tax line is added, the business case does not work.
Take the tax question to your accountant with the actual invoice structure. How a system is contracted, financed and staged affects the treatment. That is genuinely their field and not ours, and it is worth an hour of their time before you commit.
Treat "write it off" as a prompt to check, not a benefit to bank. It is a reasonable question to raise. It is not a reason to sign.
The deduction you do get is real. It is just usually depreciation over the asset's life rather than a single-year deduction, and a proposal that blurs those two is telling you something about how carefully the rest of it was built.
Instant asset write-off and solar:
your questions, answered.
Usually no. The write-off applies per asset, and the ATO publishes a $20,000 limit for businesses with turnover under $10 million for assets first used or installed ready for use between 1 July 2023 and 30 June 2026. Commercial solar systems generally cost considerably more than that, so they fall outside the instant write-off and are depreciated under the ordinary rules or through the small business pool instead.
Per asset. The ATO states the write-off can be used for multiple assets provided the cost of each individual asset is less than the relevant limit. It is not an annual allowance you can spend across a project.
The ATO's published table runs to 30 June 2026 and does not publish a limit past that date. We are not going to state one it has not published. If a proposal quotes a threshold for a system installed after that date, ask which ATO page it comes from and confirm the treatment with your accountant.
The test is when the asset is first used or installed ready for use, not when it is ordered or paid for. For commercial solar this matters near a year end, because a system can be physically installed but not yet commissioned or connected.
The same per-asset rule applies, and commercial battery systems generally cost more than the limit for the same reason solar does. Battery support in Australia comes through the Cheaper Home Batteries Program rather than the tax system, and that is a certificate discount rather than a deduction.
There is — it is just ordinary depreciation rather than an instant deduction, and its value depends on your tax rate. The point of this guide is not that the benefit is absent, it is that the benefit is routinely overstated in proposals and is the wrong reason to make the decision.
Where these figures come from.
One primary source: the ATO's own guidance page and its published limit tables. We have not restated any threshold the ATO does not publish.