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UK tax tool

Self-Assessment Helper

A hedged estimate of your 2026/27 Self Assessment outcome from employment, side income, dividends and savings.

Estimated refund ~£14

Confidence: 60%

Based on the figures provided. This is a simplified estimate and does not include Class 2 / 4 NIC, capital gains, or payments on account.

Total tax estimated
£5,486
PAYE collected
£5,500
Marginal rate band
20%
Adjusted non-savings income
£40,000
Tax on dividends
£0
Tax on savings
£0

Always confirm via your HMRC Self Assessment account or a qualified accountant before filing.

What a result looks like

Sample: £40k salary, £5,500 PAYE, £8k freelance, £1k dividends. Estimated to owe ~£1,750.

What we check

When to use this tool

What the result bands mean

Refund expected

PAYE may have over-collected.

Small bill

Possibly under £500. Check savings / dividend timing.

Larger bill

Worth setting money aside ahead of January 31.

Common mistakes

Worked example

Employment £40k, PAYE £5,500. Side gig £8k profit. Dividends £1,000.

Non-savings: £48k - PA £12,570 = £35,430 x 20% = £7,086. PAYE covered £5,500. Owed on side income: ~£1,586.

Dividends: £500 free + £500 x 8.75% = £44. Total bill ≈ £1,630.

Frequently asked questions

Do I need to file Self Assessment?

Common triggers: self-employment over £1,000, untaxed income over £2,500, dividends over £10,000, income over £150,000, child benefit at higher income.

Does this calculate Class 2 / 4 NIC?

Not in this version. Adds may be needed for self-employed profit.

What about payments on account?

Not modelled. HMRC may also bill you upfront for the next tax year.

Do you handle capital gains?

No - those need a separate computation.

What about higher-rate pension relief?

We approximate it by extending your basic rate band by the gross contribution you enter.

Related guides

Related tools

Recalculate ↑

Sources

  • HMRC: Self Assessment manual.
  • HMRC: Income Tax 2026/27 rates and allowances.
  • HMRC: Personal Savings Allowance and dividend allowance.

Last verified: 2026-05-03.

Disclaimer: Simplified estimate only. Not a substitute for filing via HMRC or speaking to a qualified accountant.