GST & BAS Quarterly Workbook (Australia) - Sales and Purchases Log with BAS Labels G1, 1A, 1B by Quarter | Excel

NEW (24 Oct 2026): Google Sheets edition included. Your download now has the Excel workbook plus a PDF with a one-click link to make your own Google Sheets copy (same formulas, checked cell by cell against the Excel version).

Built and checked by a CPA. Every formula tested against a separate calculation. 30-day money-back guarantee.

NEW in version 1.2 (22 Oct 2026): every tab now looks and works like an app screen, not a worksheet: no gridlines or row numbers, a branded header with a one-line instruction on each tab, Home and Dashboard links, cleaner tables and clearly marked input cells. Same tested formulas: every result was checked identical to the previous version.

NEW in version 1.1: a one-page Dashboard showing G1, GST on sales, GST credits and the amount owing each quarter, with charts; a clickable Home page that takes you to every tab; and a cleaner layout throughout. Same tested formulas.

Log sales and bills as they happen. Each quarter your BAS figures are ready.

What it does

• Sales and purchases logs (500 rows each) with a tax code on every line: GST, GST-free, input taxed, out of scope
• BAS tab adds it up by quarter and for the year: G1, G3, G10, G11, 1A and 1B, plus W1, W2 and T7 you enter, and the amount to pay or the refund
• Cash or accrual basis, G1 reported including or excluding GST
• Business-use % for mixed bills, bills with a different GST amount (like utilities), capital purchases
• The tax invoice rule: no GST credit on purchases over $82.50 without a tax invoice, flagged for you
• Checks tab: missing tax codes, dates outside the year, missing tax invoices, totals that agree

How it was checked

• The BAS totals were tested against a separate calculation on randomly generated sales and purchases, for both bases and both G1 options, matching to the dollar.

Good to know

• Based on the ATO’s GST bookkeeping guide for small business. Usual quarterly due dates for self-lodgers are shown; tax agents may have later dates.
• Example rows included. Designed by Plain Numbers Co with the help of AI tools.

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Important: General information and a record-keeping tool only, not tax or financial advice. Check your BAS with a registered tax or BAS agent if unsure. 30-day money-back guarantee: if it doesn't work for your situation, email hello.plainnumbersco@gmail.com within 30 days. We'll fix it, or refund you in full if you'd rather. This is in addition to your rights under the Australian Consumer Law, which are not excluded.

Licence: for the purchaser's own use. Please do not resell or share the file