How much tax should I set aside monthly? (UK self-employed)

Use your annual self-employed tax estimate to build a monthly set-aside plan. This page focuses on a simple workflow that avoids false precision.

Start from an annual estimate, then convert it into a monthly set-aside amount.
Update your plan when profit changes or when you switch tax year/region in the calculator.
Use buffers for uncertainty; this is planning, not a guaranteed bill.

A simple monthly planning workflow

Step one: run the calculator with your best annual profit estimate. Step two: take the total and divide it into a monthly set-aside amount that fits your cash flow. Step three: revisit the plan when your income or expenses change.

Why you should avoid false precision

Self-employed income can vary. Your final bill depends on official calculations and your full situation. The goal here is to create a repeatable habit: estimate, set aside, review, and adjust.

Practical tips

- Keep a separate “tax pot” account so you do not accidentally spend the set-aside.
- Review your plan after large invoices, expense spikes, or changes in other income.
- If your situation feels complex, use this as a starting point and then verify with official guidance.

Not tax advice. This page provides a budgeting method, not a legal calculation.

Open self-employed calculator How this is maintained

Last updated: 2026-04-20

FAQ

Should I set aside the same amount every month?

It depends on how variable your income is. Many people start with a steady amount and adjust when profits change.

What if I also have a salary?

Include other income in the calculator so the estimate better reflects your marginal rate, then plan from that total.

Does this include payments on account or quarterly payments?

No. This is a budgeting method based on an annual estimate. Verify official payment schedules separately.

Sources

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

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