Phone and internet costs: how do they affect my profit input?

A simple guide to avoid common mistakes with phone and internet costs and to keep your profit input consistent.

This calculator does not take expense line items; it takes profit after allowable expenses.
Mixed use services are a common mistake area; use a documented method.
When in doubt, verify official guidance rather than guessing.

What to do in this calculator

Compute annual profit using your records. If you have phone and internet costs, reflect them in your bookkeeping method first, then enter profit.

Treating a personal contract as fully business without a clear basis, or failing to separate business use where possible.

A consistent method is more useful than a complex one you cannot repeat. Use the calculator to plan, and keep GOV.UK guidance bookmarked.

Not tax advice. This page is an educational guide. For official rules, verify the sources below.

Last updated: 2026-04-20

Can I input my phone bill here?

No. Enter profit after you have accounted for it.

Do you store my data?

No. The calculator runs in your browser.

Where can I check the official rules?

Use the GOV.UK expenses guidance.

For official rules and definitions, verify with the references below.