What Is the GDP Adjustment Factor?
Each income year, businesses use a GDP adjustment factor to index their quarterly GST and PAYG instalments. This ensures instalments better reflect inflation and economic growth. In recent years, the adjustment was 4%. (softwaredevelopers.ato.gov.au)
Recent Change: The New Rate From 1 July 2026
- As of 1 July 2026, the adjustment factor rises to 5% for the 2026–27 income year. (softwaredevelopers.ato.gov.au)
- If your company has a substituted accounting period (SAP) and that period commenced in January, February, or March 2026, you’ll continue using the 4% rate because your income year started before the new adjustment comes in. (softwaredevelopers.ato.gov.au)
How It Impacts Your Instalments
- Higher Instalments: Each quarterly instalment for GST or PAYG tax will be calculated based on a higher amount, leading to more consistent payments.
- Budget for Cash Flow: Businesses should plan for increased payments; smoothing cash flows becomes more crucial.
- SAP Businesses Must Be Careful: If your income year crosses the threshold period (like starting in April 2026), the entire year will use the 5% rate. SAPs starting earlier keep 4%.
Examples
| Scenario | Accounting Period Start | Adjustment Rate | Behaviour Implication |
|---|---|---|---|
| A business with April–March year | 1 April 2026 | 5% | Entire income year adjustment at 5% |
| A business with January–December | 1 January 2026 | 4% | Even though year ends 31 December 2026, start was before 1 April so stays 4% |
Actionable Steps for Businesses
- Review your accounting period: Confirm whether you're using a standard or substituted accounting year, and when your income year commences relative to 1 April 2026.
- Estimate the new instalments: Use your recent turnover numbers to forecast higher GST and PAYG obligations under 5%.
- Adjust your cash reserves: Set aside enough to cover increased instalments, especially in first quarters under new rate.
- Check your software: Many tax software packages automatically update rates—ensure yours is aligned.
- Consult tax advisor: Particularly useful if your business has complex GST or PAYG arrangements, or if you're an SAP entity.
Key Takeaways
- 5% adjustment applies for most from 1 July 2026.
- SAPs with income years starting before April 2026 will remain at 4%.
- Expect higher instalments, rework cash flow, and double-check systems.
By adjusting early, tightening cash flow planning, and engaging your accountant or tax professional, you’ll be ready for the change without surprises.