Phone and Internet Business Use: Support the Percentage
Use an itemised bill or a documented usage sample to explain the business share of a phone or internet cost. Record what you counted, the period it covers and why it reflects normal use. A round percentage without supporting activity is hard to explain, and a sample that ignores private use can overstate the business share.
What you’ll get from this guide: Prepare an allocation worksheet with an explicit basis, supporting bill and review date.
- Choose a measurable basis that fits the cost on the bill.
- Include private activity in the total and keep the sample evidence.
- Check bundled methods before claiming the same cost separately.
This worksheet is for a sole trader or partnership using a shared phone or internet service. Use the evidence to explain your allocation instead of choosing the percentage that produces the largest claim.
Choose a basis that fits the service
The ATO's home business guidance for sole traders and partnerships describes itemised business calls as a share of total calls, and time or data use for internet costs. Where itemised information is unavailable, it describes a representative four-week diary.
Use the appropriate measure for the service. A phone call count does not explain how a shared household uses broadband. If one person streams video for hours while the business sends a few emails, counting the number of users alone leaves an obvious gap.
Fictional itemised phone bill. The sample month has no unusual holiday or promotion and includes both incoming and outgoing calls.
| Item | Calculation or evidence | Result |
|---|---|---|
| Business calls | 48 calls linked to customer and supplier activity | 48 |
| Other calls | 72 private calls | 72 |
| Total | 48 + 72 | 120 calls |
| Business share | 48 ÷ 120 | 40% |
| Illustrative bill allocation | $90 × 40% | $36 |
| Remaining share | $90 − $36 | $54 |
A call count is not automatically suitable for data use, premium call charges, a handset purchase or every bundled plan.
Keep the sample and the bill together
Record which calls or sessions relate to which business activity. You do not need to copy a customer's private conversation into the worksheet; an internal job or contact reference can explain the purpose.
Save the source export before cleaning it up. Include dates with no business use, personal activity and any excluded charges. Note whether the bill includes a device instalment, installation or a separately charged service; these may need a different treatment from ordinary usage.
Check for a cost already included elsewhere
The ATO's home business methods page explains that the fixed-rate method covers specified costs including phone and internet. Keeping this worksheet does not create a separate claim for a cost already covered by that method.
Show your agent the full method you are using, the original GST-inclusive bill and any proposed income-tax allocation. Leave the goods and services tax calculation separate. The example's $36 is simply 40% of the stated bill, not a tax result.
Communications usage allocation worksheet
Copy the template, save a text file for offline use, or print this page with its examples and sources. Fill in your own copy and check it before relying on it.
Service and account: Bill period / amount / GST shown: Method being considered: Sample dates and reason representative: Business activity units: Total activity units including private use: Allocation basis and calculation: Costs already covered by another method: Changed circumstances / review date: Tax agent decision:
Change the sample when the business changes
A marketing campaign, school holidays, a new employee or working away from home can make an old sample unrepresentative. Record the review date and why the basis still fits, or what needs changing. Don't keep applying the same percentage because the software remembers it.
Use the home work diary for hours and the record-keeping guide for the wider file.
Key takeaways
- Choose a measurable basis that fits the cost on the bill.
- Include private activity in the total and keep the sample evidence.
- Check bundled methods before claiming the same cost separately.
Where to get help
Take the worksheet, bills and chosen method to your registered tax agent. See the tax records hub for evidence templates for other mixed-use expenses.
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Where to go from here
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General information only. This guide doesn't take your personal or business circumstances into account and isn't financial, legal or tax advice. Rates and thresholds change — check the official sources linked in this guide and get qualified advice where your circumstances require it.