ATO Granny Flat Agreement Explained: CGT, Rent and Family Arrangements (2026)

An ATO granny flat agreement is a formal family deal where someone pays for the right to live in a home a relative owns, often after cash or assets help fund a secondary dwelling. When the strict conditions are met, the ATO treats qualifying arrangements differently from ordinary tenancies for capital gains tax.

This is general information, not tax or legal advice. Confirm your situation with a registered tax agent and a solicitor before money moves. Related reading: granny flat regulations by state, cost breakdown, and the cost calculator.

Why families document a granny flat arrangement

Without a written agreement, money given to Mum and Dad to build a flat can look like a gift, a loan, or informal rent. That gets messy if the relationship breaks down, someone enters aged care, or the property is sold.

• Who paid what toward construction or renovation
• Occupancy rights for life or a fixed term
• What happens on sale, death, or separation
• Whether amounts affect pensions or aged care means tests (Services Australia rules are separate: get specialist advice)

Don’t leave it as a handshake. Families do this work while everyone still agrees. Waiting until there’s a dispute is how these matters end up in court.

ATO granny flat interest: CGT in brief

Normally, transferring value into someone else’s home can trigger CGT events. The ATO provides a granny flat CGT exemption for qualifying family arrangements where a person acquires a granny flat interest in exchange for money or assets. Conditions include:

• The arrangement is in writing
• The occupier doesn’t hold legal title to the whole property
• The deal is between family members as defined by the ATO
• The consideration isn’t more than the market value of the granny flat interest

Primary source: ATO: Granny flat arrangements. If you’re unsure whether you meet the family definition, stop guessing and ask your adviser.

Rent, board and family payments

So if you’re paying “a bit of board” every week, don’t assume it’s invisible. Below-market payments can still matter for tax and for Centrelink. Keep records either way.

What the written agreement should cover

1. Parties and property description (including the council-approved secondary dwelling)
2. Amount paid or transferred and how it was valued
3. Occupancy rights (life interest versus fixed term)
4. Who pays rates, insurance, maintenance and utilities
5. Exit clauses: sale of the main house, relationship breakdown, aged care entry
6. Refund or compensation if the occupier must leave early

State property law still applies to building approvals. Tax paperwork doesn’t replace a CDC or DA. See approval process and our rules by state hub.

Common mistakes

• Verbal promises without a deed
• Paying above market for the occupancy right (the ATO may treat the excess as a gift)
• Assuming any family payment is automatically CGT-free
• Ignoring Centrelink granny flat rules for age pension assets tests
• Building without council approval, then expecting tax treatment to fix compliance

If you’re building first and documenting later, you’re doing it backwards. Lock the legal path before the concrete goes down. Don’t treat a handshake as a CGT exemption. The ATO wants writing, family definitions and a valuation that isn’t a guess.

How this ties to building costs

Construction spend should line up with documented contributions in the agreement. Use the cost breakdown and the calculator for line items before you lock in family transfers. It’s easier to value a granny flat interest when everyone can see what the build actually cost.

But don’t mix a market lease with a family occupancy right on the same person without advice. Those are two different paper trails. If Centrelink is in the picture, the deed and the tax file need to match the living facts.

Frequently Asked Questions