ACT Shelter has developed this online calculator to help tenants and landlords understand and apply the ACT’s rent increase laws. The calculator estimates the maximum increase permitted under the ACT’s CPI-linked formula, providing a practical resource while the ACT Government’s own calculator remains unavailable. Information about how rent increases work in the ACT, and relevant links, are provided below.
How rent increase limits are calculated in the ACT
In the ACT, rent increases are regulated by the Residential Tenancies Act 1997 and the Residential Tenancies Regulation 1998. These set out how often rent can be increased, how much notice a landlord must give, and a formula for working out whether a proposed increase is “excessive”.
This page explains those rules in plain language. It is general information only and is not legal advice.
The two basic limits
Two separate rules apply to every rent increase:
- Timing – rent can only be increased once every 12 months. The 12 months is counted from the start of the tenancy (for a first increase) or from the date the last increase took effect (for any increase after that). If you move from one fixed-term agreement straight into another with the same landlord, the 12 months keeps counting from the earlier date — it does not restart.
- Notice – the landlord must give at least 8 weeks’ written notice before an increase can take effect.
If your tenancy began before 10 December 2024 and is still on its original fixed term, the amount of any increase may instead be governed by what your tenancy agreement says, rather than the formula below.
How much can the rent increase?
The ABS tracks rent prices through the Consumer Price Index (CPI) — specifically the “rents” component for Canberra. Each CPI figure for a given month is called an “index number”.
The prescribed amount compares the index number at two points in time to see how much rents in Canberra generally have risen, then allows a landlord to increase your rent by that percentage rise, plus an extra 10%.
The formula set out in the Regulation is:
Prescribed amount = 1.1 × current rent × (current index number − initial index number) ÷ initial index number
In that formula:
- current index number is the most recent Canberra Rents CPI figure published by the ABS at the time the landlord gives you the notice of the increase; and
- initial index number is the Canberra Rents CPI figure that applied when you got notice of your last rent increase — or, if you’ve never had an increase, when your tenancy began.
Because the CPI figure changes over time, the maximum dollar amount a landlord can charge also changes – it is not a fixed percentage. If there has been no change in the Canberra Rents CPI since your last increase (or since your tenancy began), the prescribed amount is zero and the landlord cannot increase the rent at all.
Worked example
A tenancy began on 15 December 2024 with rent of $600 per week. The landlord wants to increase the rent from 27 January 2026, and gives notice on 1 December 2025 (more than 8 weeks beforehand).
Initial index number (Canberra Rents CPI on 15 December 2024, when the tenancy began): 99.37
Current index number (Canberra Rents CPI on 1 December 2025, when notice was given): 100.01
Applying the formula:
1.1 × $600 × (100.01 − 99.37) ÷ 99.37 = 660 × 0.0064 = $4.25
So, the rent could be increased by up to $4.25 per week — from $600 to $604.25 — without the increase being considered excessive.
Implications of changes to the way the ABS reports CPI
In late 2025, the ABS made some changes to the way CPI is calculated, moving from quarterly to monthly reporting, and re-referencing its entire quarterly index series.
These changes had implications for how the calculations for rent increases are undertaken. ACT Shelter has designed the calculator to ensure it remains consistent with the precribed method for calculating rent increases that are set out in regulation, while adjusting input data from before October 2025 to ensure mathematical consistency with the original, historically-applicable figures.
Further information about the methodology used can be found in the methodology note here.
What if the landlord wants to increase rent above the prescribed amount?
A landlord can only charge more than the prescribed amount if either:
- they tell the tenant in writing that the proposed increase is above the prescribed amount, and the tenant agrees to it in writing; or
- they apply to the ACT Civil and Administrative Tribunal (ACAT) and are granted an order allowing the higher increase.
If the tenant does not agree to an above-prescribed-amount increase, the landlord (or their agent) cannot enforce it — they must apply to ACAT and show why the higher increase should be allowed.
A tenant who thinks any proposed increase (including one at or below the prescribed amount) is excessive can also apply to ACAT to have it reviewed. This application must be made at least 2 weeks before the increase is due to take effect.
Where the CPI figures come from
The Consumer Price Index (CPI) is published monthly by the Australian Bureau of Statistics (ABS). To find the CPI rent index for Canberra, open Table 10: CPI – Group, Sub-group and Expenditure Class, Index Numbers by Capital City, then select the Index worksheet and locate Index Numbers → Rents → Canberra. These are the figures used to calculate the rent increase threshold under ACT tenancy laws.
For the second half of 2026, the release dates are as follows:
- Consumer Price Index, Australia, June 2026, Release date 29/07/2026 11:30am AEST
- Consumer Price Index, Australia, July 2026, Release date 26/08/2026 11:30am AEST
- Consumer Price Index, Australia, August 2026, Release date 30/09/2026 11:30am AEST
- Consumer Price Index, Australia, September 2026, Release date 28/10/2026 11:30am AEDT
- Consumer Price Index, Australia, October 2026, Release date 25/11/2026 11:30am AEDT
About ACT Shelter’s rent increase calculator
Because the formula above can be fiddly to apply by hand, and the ABS figures are not always easy to find, ACT Shelter has built a simple online rent increase calculator for the ACT community. You enter your current rent and the relevant dates, and it works out the prescribed amount using the published Canberra Rents CPI figures, so you can check whether a proposed rent increase is within the limit.
Caveats and disclaimer
- This calculator and this page are provided as general information only. They do not constitute legal advice, and ACT Shelter is not a legal service.
- The calculator applies the prescribed amount formula in the Residential Tenancies Regulation 1998. It assumes a tenancy that is subject to the prescribed amount rules (generally, tenancies that started, or had their most recent increase take effect, on or after 10 December 2024). It is not designed for older fixed-term agreements whose increase terms are set by the lease itself.
- Results depend on the accuracy and currency of the ABS Canberra Rents CPI figures used. ACT Shelter updates these figures periodically, but there may be a short delay after a new monthly figure is released.
- If a calculation from this tool differs from a figure provided by ACAT, Access Canberra, or a tenancy advice service, the official source should be treated as correct.
- If you are unsure whether a rent increase you have received is lawful, or you want to dispute one, contact Legal Aid ACT (or Canberra Community Law if you are a tenant of Housing ACT or an ACT community housing provider), or seek independent legal advice, or apply to ACAT for a review (see links below).
Useful links
Legislation
- Residential Tenancies Act 1997 – the main law governing residential tenancies in the ACT, including rent increases.
- Residential Tenancies Regulation 1998 – sets out the prescribed amount formula in detail.
ACT Government information
- Renting in the ACT – general ACT Government renting hub.
- Rental laws in the ACT – overview of tenant and landlord rights and obligations.
- Rent increases – the ACT Government’s own explanation of the rent increase rules.
- The Renting Book – the ACT Government’s detailed guide to renting, including how to calculate a rent increase manually.
Disputes
- ACT Civil and Administrative Tribunal (ACAT) – an independent body that can help resolve disputes between tenants and landlords, and between co-tenants, including disputes about rent increases.
Legal advice and support
- Legal Aid ACT Tenancy Advice Service – free legal advice, support and education for tenants and occupants in the ACT.
- Canberra Community Law – free legal advice for tenants of Housing ACT or an ACT community housing provider.