By Manvinder Sidhu, Co-founder, Ezyiah
Short answer: Double-entry bookkeeping records every business transaction in at least two accounts, so that debits equal credits. One side shows what came in; the other shows what went out or what you now owe. The two sides stay in balance, which is how a ledger catches errors and produces reports such as a profit and loss.
What is double-entry bookkeeping?
Double-entry bookkeeping is a way of recording money so that every transaction has two sides. If your business bank account goes down by $550, something else in the books must change by $550 as well: you may have bought tools, paid a supplier, or reduced a loan.
The two sides are called a debit and a credit. They are not "good" and "bad", and a credit does not automatically mean income. They are simply the two equal halves of an entry. When the books are correct, total debits equal total credits.
That balanced record is the ledger behind everyday reports. A profit and loss is built from income and expense accounts. A balance sheet is built from assets, liabilities and equity. Both only make sense if the underlying entries balance.
This is different from a single list of money in and money out, such as a bank statement or a simple spreadsheet of payments. A bank statement tells you what happened in one account. Double-entry tells you why, by showing the other account that moved at the same time.
How do debits and credits work?
Every account in a ledger has a normal balance — the side that increases it:
| Account type | What it records | Increases with | Decreases with |
|---|---|---|---|
| Assets | What the business owns or is owed, such as bank, receivables, equipment and GST credits | Debit | Credit |
| Liabilities | What the business owes, such as suppliers, loans and GST collected | Credit | Debit |
| Equity | The owner's interest in the business | Credit | Debit |
| Income | Sales and other revenue | Credit | Debit |
| Expenses | Costs of running the business | Debit | Credit |
So when you spend business money on materials, you debit an expense (or an asset, if you are buying equipment) and credit the bank. When a customer pays you, you debit the bank and credit income — and, if the sale included GST, you also credit the GST you have collected to send to the ATO.
You do not have to memorise the table to use software. You do need it to review an entry the software proposes, or to understand a journal your accountant posts.
What is the accounting equation?
Double-entry keeps this equation true after every transaction:
Assets = liabilities + equity
Income increases equity. Expenses decrease it. That is why a profit sits on the equity side of the business, and why a loss reduces what the business is worth to its owner.
If an entry is missing a side, posted twice, or coded to the wrong type of account, the equation breaks or the reports look wrong. Finding that break is the point of the system. A list of bank transactions can hide those mistakes; a balanced ledger surfaces them.
A worked example: buying tools and getting paid
This is an illustrative example, not a customer story. The GST figures use the ATO's one-eleventh rule for a GST-inclusive price.
Alex is a GST-registered sole-trader plumber. Two things happen in the same week.
1. Alex buys tools for $550 including GST, paid from the business account.
GST in $550 is $50. The tools themselves cost $500.
| Account | Debit | Credit |
|---|---|---|
| Tools (asset) | $500 | |
| GST credits | $50 | |
| Bank | $550 | |
| Total | $550 | $550 |
The bank went down by $550. The business now has $500 of tools and a $50 GST credit to claim on the next BAS. Nothing is "missing".
2. A customer pays $1,100 including GST for plumbing work.
GST in $1,100 is $100. The sale excluding GST is $1,000.
| Account | Debit | Credit |
|---|---|---|
| Bank | $1,100 | |
| Sales (income) | $1,000 | |
| GST collected | $100 | |
| Total | $1,100 | $1,100 |
After both entries, the bank has changed by a net $550 in ($1,100 in, $550 out). Sales show $1,000. The BAS figures show $100 of GST collected and $50 of GST credits. The same events that appear on the bank statement now also explain the profit and the GST.
For how GST itself works, see What is GST in Australia?.
Why does double-entry matter for Australian businesses?
The ATO expects you to keep most business records for five years, and it suggests using accounting software to produce tax invoices and generate GST reports at BAS time. Software that keeps a double-entry ledger is how those reports stay tied to the transactions underneath them.
That matters when something does not look right:
- a payment was coded to the wrong expense, so the profit is off but the bank still reconciles
- GST was treated as part of the sale instead of being split out, so the BAS will not match the invoices
- an owner drawing was treated as an expense, so the business looks less profitable than it is
Bank reconciliation checks that the bank account in the ledger matches the bank. Double-entry checks that every other account moved correctly at the same time. You need both.
Does accounting software still use double-entry?
Yes. Modern accounting software and AI bookkeepers still post debits and credits behind the screens you see. The software may show you a transaction list, a category and a GST code rather than a journal, but the ledger underneath is double-entry.
That is also how journals and opening balances work. A journal is a manual double-entry when there is no bank transaction to import — for example, recording depreciation, moving an amount between accounts, or correcting an earlier entry. Opening balances are the starting figures for each account when you move a set of books onto a new ledger, so the new system begins in the same position the old one ended.
Ezyiah runs its own double-entry ledger, including manual journals and opening balances. It is an AI bookkeeper that does the bookkeeping itself — it connects to your bank, proposes the coding and GST treatment, matches receipts and invoices, and prepares reports from the reconciled result — rather than sitting in front of another product. Your accountant can still open the books, review an entry and approve the figures before anything is lodged. See What is an AI bookkeeper? and how that works in Ezyiah AI.
FAQ
Is double-entry the same as having two copies of your spreadsheet?
No. It does not mean recording the same list twice. It means each transaction is posted to at least two different accounts, with equal debits and credits.
Do I need to enter debits and credits myself?
Not usually, if you use accounting software or an AI bookkeeper. You review the account and GST treatment it proposes. You (or your accountant) would still post a journal when there is no bank line to import.
What is the difference between a debit and a withdrawal?
A withdrawal is money leaving a bank account. A debit is one side of a ledger entry and can increase an asset or an expense, or decrease a liability. Crediting the bank is what records the withdrawal.
Does double-entry replace bank reconciliation?
No. Reconciliation checks that the bank account in your books matches the real bank feed or statement. Double-entry checks that the other side of each transaction was recorded correctly.
Can I do my books on a single-entry cashbook instead?
Some very small records start that way, but a cashbook will not by itself produce a balanced set of accounts, a clear GST split, or reports your accountant can review with the same confidence as a ledger. Once you are GST-registered, software that keeps a proper ledger is the practical option.
Get the two sides of every transaction recorded
Ezyiah connects to your bank, codes each transaction and its GST treatment in its own double-entry ledger, matches receipts and invoices, and prepares your reports and BAS from the reconciled data. Your accountant then reviews and approves before lodgement. Plans for businesses start from $79 a month billed yearly, and from $299 a month billed yearly for accounting firms. Prices are in Australian dollars and include GST. See how the AI bookkeeper for business owners works, or start your free trial.
This article is general information, not tax or accounting advice. Check your own situation with a registered tax or BAS agent.
Sources
- ATO, Tax invoices (one-eleventh GST rule), accessed 7 November 2026
- ATO, Overview of record-keeping rules for business, accessed 7 November 2026
- ATO, Accounting for GST in your business, accessed 7 November 2026
- Ezyiah, Changelog (Double Entry: journals and opening balances), accessed 7 November 2026
- Ezyiah, What is an AI bookkeeper?, accessed 7 November 2026
- Ezyiah, Pricing and pricing for businesses, accessed 7 November 2026
