Freelancer Tax Planner — UK Self Assessment Edition

“Save 20% for tax” is a guess, and for most sole traders it is the wrong guess in one direction or the other. This planner does the real arithmetic for the 2026/27 tax year (6 April 2026 – 5 April 2027) with editable EXAMPLE settings you verify against GOV.UK: a £52,000 turnover with £9,800 of expenses is a £42,200 profit; after the £12,570 personal allowance, income tax is £5,926.00, Class 4 National Insurance is £1,777.80 — £7,703.80 in total, 18.3% of profit, £641.98 a month. Not 20%. Yours, calculated.

What it does for you:
– Real bands, not a flat percentage: basic, higher and additional bands computed separately, with the personal allowance tapering away £1 for every £2 over £100,000 built in — the trap flat-rate sheets cannot even see.
– Class 4 done by band too: 6% between the profit limits, 2% above, on trading profit — and Class 2 handled the modern way (treated as paid at or above the small profits threshold; voluntary weeks are a setting if you are below it).
– January, defused: the planner shows the 31 January bill as it really arrives — the year’s tax PLUS the first payment on account (£11,555.70 on the sample) — and the 31 July second payment on account (£3,851.90), so the payment-on-account ambush is in your plan from April.
– The tax year, quarter by quarter: the SA Year Planner splits the year at the real 6 April / 6 July / 6 October / 6 January boundaries, and each quarter’s tax set-aside is its profit’s share of the total — the four quarters add up to the estimator’s figure exactly.
– Every rate is a yellow example setting: bands, limits and rates for 2026/27 pre-filled from published figures, ready to verify and replace when HMRC publishes new ones. (England, Wales & Northern Ireland bands; Scotland differs and is not modelled.)

What’s inside (.xlsx, works in Excel AND Google Sheets):
– Start Here — setup, the example-rates warning, and your settings (turnover, expenses, other income, pension contributions)
– Tax Estimator — profit, personal allowance with taper, income tax by band, Class 4 by band, Class 2, total, monthly set-aside, effective rate, the January and July payment-on-account figures, and the full 2026/27 example-rate settings block
– SA Year Planner — turnover, expenses, profit and tax set-aside by tax-year quarter, plus the key Self Assessment dates
– Expense Log — business spending, categorized, with a Tax Set-Aside line
– Monthly Budget — zero-based, Budget vs Actual fills itself
– Dashboard — the whole tax picture on one screen
– Monthly Summary — spending by month, Jan–Dec

Instant download. Yellow cells are yours to type in; every formula cell is locked (password sheetdaily, shown in Start Here). A sample sole trader is pre-filled so you can watch the bands work. Estimation tool only — not tax advice; verify every rate against GOV.UK / HMRC before relying on it.