Freelancer Tax Estimator — Australia BAS Edition

An Australian sole trader’s tax life runs on two clocks at once: the annual income-tax bill and the quarterly BAS. This workbook runs both, with editable EXAMPLE settings for the 2025-26 financial year (1 July 2025 – 30 June 2026) that you verify against the ATO. The sample trader — $86,000 of business income, $14,500 of expenses — owes $12,238 of income tax after offsets plus a $1,430 Medicare levy: $13,668 for the year, $3,417 per quarter as a PAYG instalment. The BAS tab then adds each quarter’s net GST on top, so the amount due each quarter is one number you knew months ago.

What it does for you:
– The full resident calculation: tax-free threshold and all four marginal bands, the Low Income Tax Offset with both phase-outs, and the Medicare levy with its low-income shade-in (10% of the excess over the threshold, capped at the full 2%) — every figure a yellow example setting for FY2025-26.
– BAS quarters that follow the financial year: Jul–Sep, Oct–Dec, Jan–Mar, Apr–Jun. Enter sales and purchases including GST; GST on sales (1A) and GST credits (1B) divide by 11 automatically — the sample year: $94,600 of sales, $8,600 of GST collected, $1,450 of credits, $7,150 net GST.
– PAYG meets GST in one amount due: each quarter’s BAS total is net GST + your PAYG instalment ($5,017 / $5,237 / $5,137 / $5,427 on the sample; $20,818 across the year) — the number you actually have to have in the bank on 28 October, 28 February, 28 April and 28 July.
– The registration line, drawn clearly: a built-in check compares your turnover with the $75,000 GST registration threshold and says which side of it you are on.
– A monthly habit underneath the quarterly bills: $1,139 a month set aside, tracked in the zero-based Monthly Budget beside your real spending.

What’s inside (.xlsx, works in Excel AND Google Sheets):
– Start Here — setup, the example-rates warning, and your settings (business income and expenses excl. GST, other income, super contributions)
– Tax Estimator — taxable income, income tax by bracket, LITO, Medicare levy, total tax, monthly set-aside, quarterly PAYG instalment, effective rate, and the full FY2025-26 example-rate settings block
– BAS Quarters — sales and purchases incl. GST by financial-year quarter, 1A, 1B, net GST, PAYG instalment, BAS amount due, due dates, and the $75,000 registration check
– Expense Log — business spending, categorized, with a Tax Set-Aside line
– Monthly Budget — zero-based, Budget vs Actual fills itself
– Dashboard — the whole tax + BAS 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 both clocks run. Estimation tool only — not tax advice; verify every rate against the ATO before relying on it.