Corrected 13 July 2026: an earlier version of this article stated the 2026 deeming period was 4 years. The schedule is 5 years for 2026 installs (6 years applied in 2025), stepping down one year every 1 January until the scheme ends after 2030. Re-checked against the Clean Energy Regulator on 10 October 2026; dollar figures below are at the 15 October 2026 price of $39.65 per STC, with the regulated round-down.
On 1 January 2026 the federal Small-scale Technology Certificate (STC) deeming period stepped down from 6 years to 5 years. The step-down repeats every January until the scheme phases out completely on 31 December 2030.
What this means in dollars
For a typical 6.6 kW system in Sydney (STC Zone 3, rating 1.382), the federal STC rebate is:
- 2025 install: floor(6.6 × 1.382 × 6) = 54 STCs ≈ $2,141
- 2026 install: floor(6.6 × 1.382 × 5) = 45 STCs ≈ $1,784
- 2027 install: floor(6.6 × 1.382 × 4) = 36 STCs ≈ $1,427
- 2028 install: floor(6.6 × 1.382 × 3) = 27 STCs ≈ $1,071
The dollar step-down is bigger in higher STC zones. On the same 6.6 kW system, crossing into 2027 costs about $436 in a Zone 1 postcode (rating 1.622, remote inland Australia) and about $397 in Darwin (Zone 2, rating 1.536), against about $317 in Hobart (Zone 4, rating 1.185).
Why is the rebate winding down?
The STC scheme runs under the Renewable Energy (Electricity) Act 2000 with a fixed end date of 31 December 2030. The "years remaining" multiplier in the rebate formula reflects how many years of expected generation can still be claimed at install. As 2030 approaches, the multiplier ticks down each January.
Should you wait or install now?
Every 1 January the same 6.6 kW Sydney system gets about $357 less in STCs. If you are going to install anyway, installing before the next 1 January keeps the higher figure; the deeming period follows the installation date.