Stop Leaving Your Bookkeeping Until BAS Time

The most common bookkeeping mistake we see small business owners make isn't a missing receipt or a GST error. It's leaving everything until BAS time.

Three months of transactions get crammed into one weekend, and the BAS comes out late, wrong, or bigger than anyone expected. This guide covers why it happens, what your numbers are actually telling you, and a simple routine that keeps BAS time calm.

What goes wrong when it all waits for BAS time

Leaving bookkeeping until BAS time versus keeping it up to date every week - Accounting Plus

Transactions land in the wrong category because there's no time to think about each one.
Receipts go missing because too many weeks have passed.
The BAS amount turns up as a nasty surprise, often with no cash put aside to pay it.
A whole weekend disappears trying to fix it, and the errors you miss carry through to the tax return.

It's almost never laziness

When we look at the books of business owners who've fallen behind, the cause is rarely a lack of effort. People put it off because nobody ever showed them what they're looking at. When you're not sure you're doing it right, avoiding it makes sense.

The fix isn't to become a bookkeeper. It's to understand a few basics well enough that the numbers stop being a mystery.

What your numbers are telling you

Your accounting software produces three reports that matter most. You don't need to read every line, but you should know what each one answers.

Profit and loss: did the business make money over a period? Income less expenses.
Balance sheet: what does the business own and owe at a point in time? Bank, debtors, equipment, against loans, creditors and tax owing.
Cash flow and bank reconciliation: does what the software says match what's actually in the bank? If the bank isn't reconciled, none of the other reports can be trusted.

Money in the bank isn't the same as profit

This is the one that catches most people out. A healthy bank balance can hide money that isn't yours, and a profitable business can still run short of cash.

Example: a $40,000 bank balance with GST, PAYG withholding, super and bills set aside leaves $18,700 that is really yours - Accounting Plus

Some of the money sitting in your account belongs to someone else:

GST you've collected belongs to the ATO and is paid with your BAS.
PAYG withholding from your employees' wages is also owed to the ATO.
Super for your employees is owed to their funds. Since 1 July 2026, under Payday Super, it generally has to be paid within seven days of each payday, not quarterly.
Bills you haven't paid yet are already committed.

Profit and cash also move at different times. Profit counts a sale when you invoice it, even if the customer hasn't paid. Loan repayments, equipment purchases and owner drawings take cash out of the bank but don't all show up as expenses in your profit. That's why you can have a profitable quarter and still struggle to pay the BAS.

A simple habit helps: move the GST and PAYG withholding into a separate tax account each week, so the money is there when the BAS is due.

A routine that keeps BAS time calm

Bookkeeping routine: 15 minutes weekly, 30 minutes monthly and a quarterly BAS check - Accounting Plus

Every week (about 15 minutes)

Reconcile the bank feed and code each transaction while you still remember what it was.
Snap and attach receipts in your software or app as you go.
Send invoices and chase anything overdue.
Move GST and PAYG withholding into your tax account.

Every month (about 30 minutes)

Run a profit and loss and compare it with last month.
Check who owes you money and who you owe.
Confirm wages, PAYG withholding and super have been processed and paid.

Every quarter (BAS time)

Review the GST report for anything odd, such as GST-free items coded as taxable.
Check that the bank and loan balances match their statements.
Lodge and pay the BAS on time. Quarterly BAS is due on the 28th of the month after the quarter ends (28 February for the October to December quarter), with extra time when it's lodged through a registered tax or BAS agent.

For the full list of dates, see our ATO Obligations Cheat Sheet 2026-27.

Want it off your plate altogether?

If the routine still won't happen, that's what we're here for. We keep your books up to date every week, prepare and lodge your BAS, and tell you in plain English what your numbers mean, so BAS time stops being a scramble.

Call 0485 065 556 or visit accountingplus.com.au.

General information only, current as at November 2026. It is not advice about your circumstances. Accounting Plus is a trading name of Resolve Accounting Plus Pty Ltd, ABN 77 168 174 310. Tax agent services are provided by Aplus Business Services Pty Ltd, registered tax agent 26349024.