Free tax calculator

The Safe-to-Spend tax calculator for UK sole traders.

Enter your monthly takings and expenses. This free self-employed tax calculator works out your income tax, National Insurance and VAT to 2026/27 HMRC rates — and shows exactly how much is actually yours to spend.

TL;DR

Safe-to-Spend = profit − income tax − National Insurance, after setting VAT aside. It stops you spending money that belongs to HMRC.

How the calculator works

Being self-employed means no one deducts tax before you get paid. Every payment that lands in your account is a mix of your money and HMRC's money — and it is dangerously easy to spend the lot. This calculator separates the two in four steps:

  1. Set VAT aside. If you are VAT registered, 20% of your takings (the takings ÷ 6 VAT element) is held for your next VAT return.
  2. Work out profit. Net sales minus your business expenses gives your profit for the month.
  3. Reserve income tax. Your profit is annualised and taxed at 2026/27 bands (20% / 40% / 45%) above the £12,570 personal allowance.
  4. Reserve National Insurance. Class 4 NIC is applied at 6% between £12,570 and £50,270 of profit, and 2% above.

Whatever survives all four is your Safe-to-Spend — the honest number. The live ForgeDash app does this automatically from your real invoices and expenses, so you never have to type figures in again.

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Tax calculator FAQs

How is Safe-to-Spend calculated?

Safe-to-Spend takes your monthly takings, removes the VAT element (if you are VAT registered), subtracts your business expenses to get profit, then sets aside income tax and Class 4 National Insurance based on your annualised profit. What is left is the money that is genuinely yours to spend — HMRC has already been accounted for.

Does this tax calculator include VAT?

Yes. If you toggle "VAT registered" on, the calculator treats your takings as VAT-inclusive and holds back the 20% VAT element (takings ÷ 6) for HMRC before working out profit. Turn it off if you are below the VAT threshold and not registered.

What tax year and rates does it use?

It uses UK 2026/27 rest-of-UK rates: a £12,570 personal allowance, 20% basic rate to £50,270, 40% higher rate to £125,140, 45% above that, plus Class 4 NIC at 6% between £12,570 and £50,270 and 2% above. It does not include student loan repayments, pension contributions or Scottish income tax bands.

Is this calculator accurate for my Self Assessment?

It is a fast estimate, not a filed figure. It assumes your current month is representative of the whole year and excludes reliefs like pension contributions and the trading allowance. Inside the ForgeDash app the exact numbers are computed in the database against your real transactions.

Do I need to be VAT registered to use it?

No. Most sole traders start below the VAT threshold. Leave the VAT toggle off and the calculator works purely on income tax and National Insurance. Switch it on once your rolling 12-month turnover approaches the registration threshold.

Is the Safe-to-Spend calculator free?

Yes, completely free with no sign-up. The full ForgeDash app — which tracks this automatically from your invoices and expenses in real time — is also free forever on the Essential tier.