How much tax should I save each month?

A practical method for setting aside money based on an annual estimate and official payment concepts, without false precision.

Use an annual estimate as your starting point, then translate it into a repeatable monthly habit.
Keep a buffer because real outcomes depend on your full situation and official calculations.
If payments on account apply to you, confirm the official concept on GOV.UK and plan cash flow accordingly.

A simple method

Run the calculator with your best profit estimate. Divide the total into a monthly set aside amount. Store it separately so it is not accidentally spent.

Adjust as you learn

If profit changes, rerun the estimate and update your plan. The goal is consistency, not perfect prediction.

Common mistakes

Saving nothing until year end, treating an estimate as guaranteed, or ignoring payment timing concepts.

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

Open self-employed calculator How this is maintained

Last updated: 2026-04-20

FAQ

Is the monthly amount exact?

No. It is a budgeting method.

What if my income is seasonal?

Use the same method but revisit more often and keep a bigger buffer.

Where can I learn about payment timing?

Use GOV.UK payments on account guidance.

Sources

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

https://www.gov.uk/understand-self-assessment-bill/payments-on-account