Two words appear next to every STP: binding and non-binding. They refer to how legally firm the number is.
Binding
The binding STP is the legal figure that applies to a compliance year. It is set by the Minister by 31 March of that year, after the Clean Energy Regulator prepares the calculation. Retailers must surrender certificates in line with it. The 2026 binding STP is 11.67 per cent. It carries the cumulative adjustment, which pulls in the past year’s surrender mismatches.
Non-binding
Non-binding STPs are estimates published for later years so that retailers can plan. The regulator’s page currently shows 10.75 per cent for 2027 and 7.77 per cent for 2028. They use similar methodology but exclude the cumulative adjustment, since that only applies to the binding calculation. The numbers can move as forecasts of installations, deeming periods and policy change.
When is it released
The binding percentage lands by 31 March each year. In 2026 the regulator’s page was last updated on 18 September 2026, which shows that it is maintained as a live reference. Non-binding estimates are typically refreshed with the modelling reports, and the January 2026 projections by consultants are among the inputs the regulator uses.
2027 forecast
The 2027 non-binding estimate of 10.75 per cent is a decline of under one percentage point from 2026. That is consistent with falling certificate creation as the solar deeming period drops from five years for 2026 installs to four for 2027, as in the January 2027 changes.
2030 forecast
At the time of writing the regulator’s non-binding estimates stop at 2028, so there is no official 2030 STP. The scheme ends for new installations on 31 December 2030, and the deeming period reaches one year in 2030, so the underlying creation falls sharply. Treat any 2030 number you see as an extrapolation. Whether the scheme will extend is covered in whether the STC scheme will extend past 2030. The mid-scale expansion from 1 October 2026 and batteries also complicate the forecasting, and the regulator’s models will need to absorb them.
Why the estimates move
Three things shift a non-binding figure between releases. The first is the installation forecast, which depends on rooftop uptake and on how many households wait for or rush ahead of a rebate step. The second is policy, since batteries, mid-scale solar and any scheme extension change how many certificates are created and who buys them. The third is the electricity side of the ratio: if retailers acquire less liable electricity than expected, the same number of certificates needs a higher percentage. A move of a point or two between releases is ordinary and does not signal a market problem.
What this means for installers
The non-binding path points down, which matches the 2030 end date. It does not change what you are paid per certificate on a given day. For that, check the pricing page and the deeming period explainer. The overall mechanics sit in how STC trading works.