Phone and internet costs

Partial

If you have a dedicated business phone or SIM, the full cost is deductible. If you use a personal phone for both work and personal calls, only the business-use proportion is claimable. Estimate the percentage from your call logs or usage. Broadband used partly for work can be claimed on the same proportionate basis.

Common questions

I use my personal mobile for business calls. Can I claim the bill?

Only the business-use proportion. Estimate what percentage of your calls are work-related and claim that fraction of the monthly bill.

I have a separate SIM just for work. Can I claim it?

Yes, in full. A dedicated business line is 100% deductible.

Can I claim my home broadband if I do my quotes and invoices at home?

The business share, yes. Example: a £30 a month broadband bill where roughly half the use is running the business gives a £15 a month claim, £180 over the year. Keep a note of how you arrived at the split.

Watch out for

Keep a sample of call logs to justify any estimated business-use percentage if HMRC asks.
A bundle that includes TV or streaming: only the phone and internet element supports a business share. The entertainment part is personal.
The home-office flat rate does not include phone or internet. Claim the business share of these separately, whichever home-office method you use.

Common mistakes

Claiming 100 per cent of home broadband the whole family uses. Only the business share qualifies.
Assuming the home-office flat rate covers phone and internet, and claiming nothing. It does not; the business share is claimable on top.

Cash basis vs traditional accounting

Phone and broadband bills are a day-to-day expense on both methods, deducted in the period you paid them.

HMRC sources

https://www.gov.uk/expenses-if-youre-self-employed

Last verified: August 2026 · Tax year 2026/27

Related guides and tools

Self-employed tax, explained Self-employed tax calculator

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This guidance is for general information only. Tax rules change. Verify with HMRC or a qualified accountant before filing.

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