Mobile Phone & Internet Split – Claiming the Work Portion Without Guessing

Updated: 08/09/25 • Reviewed by: GoTax Registered Tax Agent

If you use your mobile or internet for work, you can claim a portion as a tax deduction. The trick is getting the split right. In 2025, the ATO expects proof — diaries, logs, or usage breakdowns. Guesswork won’t cut it. Here’s how to claim without drama, maximise your refund, and stay off the ATO’s naughty list.

Why Guessing Will Cost You

You scroll socials, send work emails, and stream Netflix on the same phone. You pay one internet bill for the whole family. At tax time, you think: “Eh, I’ll just call it 70% work use.”

Wrong move. The ATO doesn’t like “guesstimates.” Without proof, you risk losing the deduction — or worse, getting audited.

ATO auditors don’t need to dig too deep. They know what a “normal” work percentage looks like for most industries. A tradie won’t have 90% internet use. A freelancer probably won’t use only 5%. That’s why a little diary or usage record is your best mate.

How to Work Out the Split

Mobile phone claims:

• Keep a 4-week diary showing work vs personal calls.

• Apply that percentage across the year.

• Example: 30 work calls out of 100 = 30% deductible.

Internet claims:

• Record usage over a typical month.

• If 60% of the household data is work-related, that’s your claim.

• Example: $100 monthly internet bill × 60% × 12 months = $720 claim.

Tip: If your work % changes during the year, keep another diary.

Worked Examples – Real Life Numbers

Example 1: Freelancer Designer

Jade earns $85,000 designing websites. She keeps a diary and logs:

• 70% of her internet is used for work (uploading sites, video calls).

• 30% of her mobile use is work-related.

Her bills:

• Internet = $120/month × 12 = $1,440. Work % = $1,008 claim.

• Phone = $80/month × 12 = $960. Work % = $288 claim.

Total claim = $1,296.

Example 2: Tradie with a Work Ute

Tom runs a plumbing business. He uses his phone for calls to suppliers and clients but internet is all personal.

• Phone plan = $100/month × 12 = $1,200. Work use 40% = $480 claim.

• Internet claim = $0.

Total claim = $480.

Example 3: Hybrid Employee/Freelancer

Sara works part-time as an employee (3 days/week) and freelances on the side (2 days/week).

• Internet = $100/month × 12 = $1,200. She logs 50% for freelance work → $600 claim.

• Phone = $60/month × 12 = $720. 40% work use → $288 claim.

Total claim = $888.

Comparison Table – Who Claims What?

The Top 5 Mistakes People Make

1. Guessing without proof – claiming “about 70%” with no diary.

2. Double claiming – both partners in the household claiming the full internet bill.

3. Ignoring family use – kids chewing data on Netflix but claiming 100%.

4. Forgetting depreciation – new phone over $300 depreciates, not instant.

5. Not updating records – work % changed during the year but stuck with one old diary.

Audit Horror Story

Meet Sarah, a consultant. She claimed 80% of her internet bill without a diary. The ATO asked for proof. She couldn’t provide it. Result: deduction denied, refund reduced, plus interest.

Now meet Nick, a rideshare driver. He logged every call, every gig, and his phone usage diary matched perfectly. The ATO gave him the thumbs up, and he walked away with an extra $900 on his return.

Tools to Make It Easy

• Deduction Grabber – snap receipts and store them safely for claims.

• eCashBooks (www.ecashbooks.com.au) – track bills, invoices, and usage, especially handy for ABN holders.

• GoTax Online – finalise your return in 3 easy steps with built-in prompts to remind you about work-related deductions.

FAQs – Phone & Internet Deduction Questions (Expanded to 12)

1. Can I claim 100% of my phone and internet?
   Only if they’re 100% for work — rare unless it’s a dedicated device.

2. What proof does the ATO want?
   A 4-week diary, usage records, or itemised bills. Random percentages won’t fly.

3. What if my kids use the internet too?
   Apportion the usage. If half is family streaming, only claim the work portion.

4. Do freelancers and ABN holders claim differently?
   No — same rules, just reported through the Small Business Schedule.

5. Can I claim a new phone or modem as well?
   Yes, if used for work. Under $300 = instant deduction. Over $300 = depreciate.

6. What if I work partly from home and partly onsite?
   You can still claim the work portion of calls/emails/data, even if not always at home.

7. Is Netflix or gaming deductible?
   Nope. Only work-related internet is deductible.

8. Can I just estimate the split?
   No — you need a representative record. Estimates are audit bait.

9. How long do I keep records?
   5 years. The ATO doesn’t forget.

10. Can I use an app to track usage?
    Yes — logs from your telco or usage apps are accepted.

11. Can I claim both personal and business phones?
    If you genuinely have two devices, yes — but keep records for both.

12. What if my employer already reimburses me?
    You can’t double dip. Only claim out-of-pocket costs not already paid back.

Related Reading

• Essential records to keep: https://www.gotax.com.au/blog/essential-tax-records-what-to-keep

• Home office expenses guide 2025: https://www.gotax.com.au/blog/home-office-work-from-home-expenses-guide-2025

• Internet claims explained: https://www.gotax.com.au/blog/how-much-of-your-internet-can-you-claim

Browse more in the GoTax Online Library: https://www.gotax.com.au/blog

Quick Checklist

• Keep a 4-week diary (phone/internet)
• Apply % across the year
• Claim only the work portion
• Keep records 5 years
• Use GoTax to finalise correctly

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