There are two different situations, and they claim very differently. Pick yours first.
Employee working from home
You can claim running costs (power, internet, phone, stationery, depreciation of your desk and computer). You generally can't claim rent, mortgage interest, rates or insurance. See claiming work-from-home running costs.
Running a business from home
If an area is set aside only for your business (a place of business, not just a desk), you may also claim a share of occupancy costs: rent, mortgage interest, rates, house insurance. Floor area is the usual way to work out the share. Claiming occupancy costs can affect the main residence CGT exemption when you sell.
Measure your space
Measure the office room and the whole home (internal floor area). The tool works out the percentage, and you can apply it to your yearly occupancy costs.
Estimate only. Occupancy costs apply only to a genuine place of business at home, not to employees working from home.
Step by step
- Decide which situation you're in (above).
- Measure and keep a floor plan or photo with the measurements.
- Keep a full year of bills: rent or interest statements, rates, insurance, power.
- Apply your business-use percentage only to the costs you're allowed to claim.
- Keep records for five years.
Sources
Figures checked 1 November 2026.