When do Australian rental property deductions need to be apportioned?

Draft PCG 2025/D6 says apportionment can be needed when property expenses relate partly to income-producing use and partly to another use, such as private use, part-property rental, family or below-market rental, or a loan with mixed income-producing and personal purposes.

What are the ATO time-based and area-based apportionment methods?

The time-based method looks at days used or held to produce income compared with the days owned in the income year. The area-based method looks at the floor area used to produce income, including an appropriate treatment of shared areas. Some arrangements need both methods.

What records support Australian rental deduction apportionment?

Useful records include booking calendars, owner-use dates, floor plans, area calculations, market rent evidence, lease terms, loan statements, redraw purpose evidence, refinance records, and accountant working papers.

2 May 2026 7 min read

Australian Rental Deduction Apportionment: Time, Area, Family, and Redraw Traps

An Australia-wide landlord guide to Australian Taxation Office rental deduction apportionment, including time-based, area-based, family rental, below-market rent, and loan-purpose evidence.

Part 8 of the Rental Rule Changes Watch 2026 series.

Australian rental deduction apportionment is about splitting costs when a property is not used only to earn rent. The Australian Taxation Office draft guidance focuses on fair and reasonable methods, especially time-based and area-based calculations. The evidence file should show the calendar, floor area, rent terms, market-rate support, loan purpose, and working behind every split deduction.

Apportionment is where many rental tax files become fragile.

A landlord may know the final deduction figure. The accountant may know the method. But if the calendar, floor plan, rent appraisal, loan statement, or redraw evidence is missing, the number is harder to defend later.

This article covers Australia-wide federal tax guidance from the Australian Taxation Office. It does not cover Australian state or territory tenancy law.

For the broader watchlist, read Australia Rental Tax Changes 2026: What the ATO Is Watching.

The Draft Guidance Landlords Should Know

The main source is Australian Taxation Office Draft PCG 2025/D6, which sets out an ATO compliance approach to apportionment of rental property deductions.

The draft guideline says apportionment may be required where property expenses relate partly to income-producing use and partly to another use, such as private or domestic use.

It also says taxpayers need records to support why the guideline applies and how the apportionment calculations were made.

That last sentence is the practical one. Do not keep just the final spreadsheet. Keep the documents behind the spreadsheet.

The Main Apportionment Traps

Trap	What goes wrong	Evidence to keep
Time	Full-year costs claimed despite private use or unavailable days	Calendar, booking records, owner-use dates
Area	Whole-property costs claimed when only part is rented	Floor plan, room measurements, shared-area working
Family or friends	Below-market rent treated like a normal investment rental	Lease, market rent evidence, relationship notes
Holiday home crossover	Ownership costs claimed despite private recreation use	PCG 2025/D7 risk-zone evidence, booking calendar
Redraw or refinance	Interest claimed on funds used personally	Loan purpose evidence, redraw history
Change of use	A property changes from rental to private, or private to rental	dated notices, move-in/move-out evidence

Time-Based Apportionment

Draft PCG 2025/D6 describes a time-based method for working out deductions when a property is used or held for income-producing purposes for only part of the year.

The key evidence is:

days rented
days genuinely available for rent on commercial terms
days used privately
days blocked for family or friends
days unavailable for repairs or other reasons
dates of a clear change in use

The ATO draft guidance also looks at whether a property is genuinely available on commercial terms. That means the document file should show more than a listing existed.

Keep:

platform calendar exports
agent reports
listing screenshots
rate comparisons
booking enquiries and responses
notes on why blocked or unavailable days occurred

Area-Based Apportionment

Area-based apportionment matters when only part of a property is used to earn rent.

Examples include:

renting a room in a home
renting a lower level while living upstairs
short-stay use of part of a property
shared common areas
granny flat or studio arrangements where costs overlap

Useful records include:

floor plans
measurements of exclusive tenant areas
measurements of shared areas
photos showing access and layout
utility split working
cleaning or maintenance split working
notes on which spaces guests or tenants could actually use

If a part-property rental is also only rented for part of the year, the method can become both area-based and time-based. That is where clean source documents matter.

Key Takeaway

A rental apportionment percentage should not be a mystery number. It should trace back to a calendar, floor area, market evidence, loan-purpose record, or other source document.

Family and Below-Market Rentals

Draft PCG 2025/D6 discusses rentals to family or friends at non-market rates.

If the property is rented below market for private or domestic reasons, deductions may need to be limited or apportioned. If the property is rented to family or friends at market rates, the key evidence is how the market rate was calculated at the time.

Keep:

signed lease or licence agreement
market rent appraisal
comparable rental listings from the same period
property manager advice
bank records showing payments
notes explaining any discount
accountant working papers

Do not rely on a later memory that the rent was “about market”. Keep the market evidence from the time the rent was set.

Redraws, Refinances, and Loan Purpose

Draft PCG 2025/D6 says that if a mortgage secured against a rental property, or a re-mortgage, is not all used for an income-producing purpose, you cannot claim all interest expenses.

The draft guidance also notes that redraw amounts are not treated as relating to the original purchase of the rental property. They relate to what was purchased with the withdrawn amounts.

That means interest evidence is not just the bank’s annual statement.

Keep:

original loan agreement
settlement statement
refinance documents
redraw transaction history
evidence of what each redraw funded
split-loan calculations
accountant notes on deductible and non-deductible portions

A redraw used for a car, holiday, school fees, or private renovation is a different tax story from a redraw used for deductible rental repairs.

How To Build The Evidence File

For each Australian rental property, keep an apportionment folder with:

annual rental calendar
private-use calendar
availability and listing evidence
floor plan and area calculation
family or related-party rent evidence, if relevant
loan-purpose and redraw records
expense category notes
accountant working papers
final tax-return reconciliation

That folder should sit beside the broader rental tax file described in Australia Rental Tax Changes 2026: What the ATO Is Watching.

Source Note

This article covers Australia-wide federal tax guidance from the Australian Taxation Office. It relies primarily on Draft PCG 2025/D6 and Draft TR 2025/D1. It does not cover state or territory tenancy law.

Rental Rule Changes Watch 2026

Published guides in this series:

Keep Reading

The Short Version

Australian rental deductions may need apportionment when expenses support both income-producing and private use.
Draft PCG 2025/D6 focuses on fair and reasonable methods, especially time-based and area-based working.
Family and below-market rentals need market-rate evidence.
Redraws and refinances need loan-purpose records, not just annual interest statements.
Every apportionment number should trace back to a source document.

Suggested citation

ProppiAI Editorial Team, "Australian Rental Deduction Apportionment: Time, Area, Family, and Redraw Traps", ProppiAI, 2026-05-02.

Sources used

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