If you use your personal phone or home internet for work, you can claim the work-related proportion of the cost as a tax deduction. The key is identifying what percentage of your usage is for work — and keeping records to support that percentage. The ATO accepts a 4-week representative usage diary for this purpose.
What You Can Claim
| Expense | What is deductible |
|---|---|
| Mobile phone calls | Work proportion of total call costs |
| Mobile data | Work proportion of data usage |
| Monthly phone plan cost | Work proportion of the full monthly fee |
| Home internet | Work proportion (for work-from-home, if not already covered by the WFH fixed rate) |
| Work-specific apps or subscriptions | Work proportion of cost |
Note: If you are using the WFH fixed rate method (67c/hour), phone and internet are already included in the rate. Do not separately claim them as well — that would be double-counting.
How to Calculate the Work Proportion — 4-Week Diary
The ATO accepts a 4-week representative period for phone and internet. During those 4 weeks, record:
For phone calls:
- Number of work calls vs personal calls
- Duration of work calls vs personal calls
For data:
- An estimate of data used for work vs personal (e.g., sending emails, accessing work systems) vs personal browsing, streaming
At the end of the 4 weeks, calculate the percentage: $$\text{Work proportion (%)} = \frac{\text{Work use minutes or data}}{\text{Total use minutes or data}} \times 100$$
Apply that percentage to your annual phone and internet costs.
Example Calculation
Suppose in your 4-week diary:
- Total mobile calls: 500 minutes. Work calls: 150 minutes = 30% work use
- Mobile data: 20GB total. Work data: 4GB = 20% work use
- Monthly phone plan: $80 (includes calls and data)
Annual phone cost: $80 × 12 = $960
Conservative blended estimate: 25% work use (average of 30% call and 20% data)
Phone deduction: $960 × 25% = $240
For home internet:
- Monthly bill: $90
- Estimated work proportion: 20% (office worker who does some work from home)
- Internet deduction (if not using WFH fixed rate): $90 × 12 × 20% = $216
Using the ATO’s De Minimis Approach
For very minor work phone use (e.g., rare work calls on a personal plan), the ATO allows a small reasonable estimate without a diary — but it must be genuinely minor. If your claim is above $50 in total for phone, the ATO expects a usage diary.
Employer-Provided Phone
If your employer provides you with a phone or data plan, you cannot claim those costs — they are not your expense. If your employer provides a partial reimbursement, you can only claim the out-of-pocket portion above the reimbursement.
Record-Keeping
- 4-week diary — kept once for the year, unless circumstances change significantly
- Phone bills — at least for the months covering your diary period
- Annual plan cost — total amount paid for the year
Keep records for five years.
Frequently Asked Questions
I use my phone mainly for personal use. Is the work proportion still deductible? Yes — even if it is a small percentage, the work proportion is deductible. A 10% work use on a $960/year plan gives a $96 deduction. It is worth claiming with a diary to substantiate it.
My employer pays for a phone. Can I also claim my personal phone’s work use? If you use your personal phone for work tasks beyond what your work phone covers, the extra personal phone work use may be deductible. Document what you use each for.
What if I don’t have detailed phone bills (e.g., on a flat rate plan)? For flat-rate plans (where calls and data are unlimited or capped at a fixed monthly fee), estimate the work proportion by time or activity rather than by cost of individual calls. The 4-week diary approach applies to the monthly fee amount.
Can I claim a phone bought for work? Yes. If the phone costs over $300, depreciate it over its effective life (3 years for smartphones) at the work-use proportion. If it cost $300 or less and is primarily for work, claim it in full in the year of purchase.
This article provides general tax information. For advice tailored to your situation, speak with a registered tax agent. Find one through the Tax Practitioners Board register.