How to Do Your Own Bookkeeping: A Monthly Routine for Owners

You can do your own bookkeeping with four things: one bank account used only for business, accounting software with a live bank feed, twenty minutes a week to reconcile, and a monthly close checklist you actually run. Most sole traders and small companies with a few staff don't need someone else doing data entry — they need a routine that stops the shoebox forming. Here's that routine, plus the coding mistakes that quietly cost owners money at BAS time.

Set the system up once

The setup takes an afternoon and saves you the rest of the year.

One business account, one business card

Open a separate business transaction account and run every dollar of business income and expense through it. Sole traders aren't legally required to have one, but mixing personal and business spending is the biggest reason bookkeeping blows out. Every mixed transaction becomes a decision you make twice — once now, once again in ten months when you can't remember what the $340 hardware purchase was for.

If you operate through a company, keep the separation strict — personal spending from the company account creates loan account problems your accountant has to unwind at year end. Then open a second savings account for tax money and never spend from it.

Software with bank feeds, not a spreadsheet

A spreadsheet is fine if you're not registered for GST, have no staff and process fewer than about 20 transactions a month. Past that, use software with a bank feed: transactions import automatically, you code them, and the software builds your BAS and profit and loss statement. Once you employ anyone it's effectively compulsory, because every pay run must be reported to the ATO through Single Touch Payroll on or before payday. Our comparison of accounting software for Australian small business covers the options and costs.

Set up bank rules for anything that repeats — rent, phone, insurance, merchant fees, fuel. Ten well-written rules will pre-code half your feed.

Choose cash or accruals and stick with it

If your aggregated turnover is under $10 million you can account for GST on a cash basis, meaning GST is counted when money actually moves rather than when you issue the invoice. Cash basis suits businesses that get paid slowly, because you don't hand the ATO GST on an invoice the customer hasn't paid yet. Accruals gives a truer picture of profitability month to month. Pick one, tell your accountant, and don't switch mid-year without advice.

Capture receipts at the point of purchase

You need a valid tax invoice to claim a GST credit on any purchase over $82.50 including GST. Photograph receipts into your software's mobile app as you buy — thermal paper fades, emailed invoices get buried, and a receipt you can't produce is a deduction you lose along with the GST credit.

The weekly 20-minute reconcile

Same time every week. Put it in the calendar.

Code the bank feed. Work top to bottom. Anything a rule already coded, glance at and approve.
Park what you can't identify. Create a holding account (most software calls it suspense or "ask my accountant") and put unknowns there with a note, rather than guessing. Guesses become permanent.
Attach receipts to anything over $82.50 while you still remember the purchase.
Send invoices for work completed this week, and check who hasn't paid. Chasing at seven days overdue works far better than chasing at sixty — our guide to chasing unpaid invoices has the escalation sequence.
Glance at the balance against what's due out in the next fortnight.

Twenty minutes weekly beats three hours monthly, because the memory is fresh and the pile never gets intimidating enough to avoid.

The monthly close checklist

Run this in the first week after month end.

Step	What you're doing	Time
1. Reconcile every account	Bank, credit card, PayPal, Stripe, Square. The statement closing balance must match the software exactly — not approximately	15 min
2. Clear the holding account	Chase the three transactions you couldn't identify, then code them properly	10 min
3. Chase overdue invoices	Run the aged receivables report and contact everyone past due	15 min
4. Check bills and subscriptions	Enter unpaid supplier bills so the software knows what's owed, and cancel anything you're no longer using	10 min
5. Check payroll and super	Confirm STP was filed for every pay run and that super has actually landed in each fund	10 min
6. Read the P&L and balance sheet	Compare this month to last month and to the same month last year. Investigate anything that moved more than about 20%	15 min
7. Move the tax money across	Transfer GST, PAYG withheld and income tax provision into the tax account	5 min

Step 6 is the one owners skip and the one that pays — numbers only become useful when you look often enough to notice a trend. If the report doesn't make sense yet, start with our profit and loss statement guide.

Set aside the money that was never yours

Three pools of cash in your account belong to someone else:

GST. One eleventh of every GST-inclusive sale is GST you collected on the ATO's behalf, less the GST credits on your purchases.
PAYG withholding. Tax withheld from employee wages is the employee's tax, held by you until the BAS.
Super. 12% of qualifying earnings for every employee (as at September 2026).

A common starting point for income tax is setting aside 25–30% of net profit, but the right figure depends on your structure and your marginal rate, so confirm it with your accountant rather than guessing.

Quarterly: BAS and instalments

Quarterly BAS due dates for 2026–27 are 28 October 2026, 28 February 2027, 28 April 2027 and 28 July 2027 (as at September 2026). Where a due date falls on a weekend or public holiday you have until the next business day — 28 February 2027 is a Sunday, so that one is really 1 March 2027. Lodging through a registered BAS or tax agent usually buys extra time.

Lodging late triggers a failure-to-lodge penalty of one penalty unit for each 28 days (or part thereof) the statement is overdue, capped at five units. At $364 per penalty unit, a small entity that lets a BAS drift five months is looking at $1,820 — before any interest on the unpaid GST.

If your GST turnover is under $10 million you report under Simpler BAS, which means just three GST fields: G1 total sales, 1A GST on sales and 1B GST on purchases. You don't need to complete a GST calculation worksheet.

Your BAS prep is short if the monthly close is done:

Reconcile all three months and clear the holding account
Run the GST reconciliation report and check the total sales figure against your P&L
Check no GST has been claimed on wages, drawings, loan principal or international purchases
Confirm PAYG withholding matches your STP totals for the quarter

One quarterly job has now moved: since 1 July 2026 super must reach the employee's fund within seven business days of payday, not quarterly (20 business days for a new employee's first contribution). Super is now part of every pay run, so build the payment into the payroll routine rather than a quarterly reminder.

Coding mistakes that cost money

These are the errors that show up most in small business files.

Mistake	Why it hurts	What to do instead
Claiming GST on bank fees, ASIC fees, council rates and most government charges	These generally have no GST in them, so you're claiming a credit that doesn't exist	Code them GST-free or BAS excluded
Coding an equipment purchase straight to an expense account	Overstates expenses, hides the asset, and complicates depreciation or the $20,000 instant asset write-off	Code to a fixed asset account and let the accountant decide the treatment
Coding a whole loan repayment as an expense	Only the interest portion is deductible; the principal is a balance sheet movement	Split it: principal to the loan liability, interest to an expense account
Coding owner drawings as wages	Sole trader drawings aren't a deduction, and a company paying a director creates PAYG and super obligations	Code drawings to equity, and talk to your accountant about how you should be paid
Claiming full GST on business assets used privately	The credit must be apportioned for private use	Claim the business-use percentage and keep a note of how you worked it out
Guessing GST-free versus BAS excluded	Both show zero GST but land in different BAS fields	Check our guide to GST-free versus BAS excluded

Annual: the handoff to your accountant

Do the year-end close in July, while you still remember the year. Reconcile every account to 30 June, chase the last debtors, write off anything genuinely uncollectable, count stock if you carry it, and finalise your STP data for employees.

Then send your accountant a short package: access to the software file, closing bank and loan statements at 30 June, details of any asset bought or sold, and the questions you parked during the year. Accountants bill for time spent fixing books, not reading tidy ones.

Keep records at least five years from when you prepared them or completed the transaction, in English and in a form you can produce on request. Payroll records need to be kept longer, so treat seven years as the working rule for anything employee-related.

When to hand it over

Do your own books while the volume is low and the structure is simple. Hand it over when any of these are true:

You've lodged a BAS late, or you're lodging on estimates instead of reconciled numbers
You employ more than about three or four people, especially across different awards
You have stock, multiple entities, foreign currency or a trust
An hour of your billable time is worth more than a bookkeeper's hourly rate
You dread it, and the avoidance has become a compliance problem

A middle path works well: keep coding the bank feed yourself weekly, and pay a registered BAS agent to review and lodge quarterly. Our guide to hiring a bookkeeper or BAS agent covers what to pay and how to check they're registered.

Key takeaways

The system is four parts: separate bank account, software with bank feeds, a weekly 20-minute reconcile and a monthly close checklist.
Twenty minutes weekly beats a monthly catch-up, because you still remember what each transaction was.
Move GST, PAYG withholding and super into a separate account as it's earned — that money was never yours to spend.
Quarterly BAS for 2026–27 is due 28 October, 28 February, 28 April and 28 July; late lodgement costs up to five penalty units at $364 each (as at September 2026).
Super now has to reach the fund within seven business days of payday, so it belongs in your payroll routine, not a quarterly one.
Keep records five years, or seven for anything payroll-related, in English and readily accessible.

Where to get help

ATO — record keeping for business (ato.gov.au) for what to keep, how long, and the electronic record rules
ATO — business activity statements for due dates, Simpler BAS and lodging through Online services for business
ATO — Payday Super for the seven-business-day rule and qualifying earnings
Tax Practitioners Board register (tpb.gov.au) to confirm a bookkeeper is a registered BAS agent before they lodge anything for you
business.gov.au for record keeping and finance basics
Your accountant or registered BAS agent for your chart of accounts, cash versus accruals, the right tax set-aside percentage, and anything involving drawings, loans or assets