The accounting equation: how every transaction stays in balance
Assets = liabilities + equity, explained properly: what each element means, the expanded equation, a nine-transaction worked example and the mistakes that throw it out of balance.
Foundations · Updated 21 October 2026
The accounting equation is the idea that holds the whole of double-entry bookkeeping together:
Assets = Liabilities + Equity
It says that everything a business controls (its assets) has been financed from one of two places: money owed to outsiders (liabilities) or the owners' stake (equity). Because those are two descriptions of the same resources, the two sides must always be equal. Not usually equal, not equal at the year-end — equal after every single transaction.
If you understand the equation, debits and credits stop being a list of rules to memorise. They become a way of recording which side of the equation moved, and by how much.
The three elements
Assets are resources the business controls as a result of past events that can bring it economic benefits: cash, money customers owe (accounts receivable), inventory, equipment, buildings, software licences, prepaid rent. The test is control and benefit, not legal ownership alone — a leased van can be an asset of the business using it.
Liabilities are present obligations to transfer resources to someone else because of something that has already happened: supplier bills not yet paid (accounts payable), bank loans, wages earned by staff but not yet paid, customer deposits for work not yet done, tax owed.
Equity is what's left for the owners once liabilities are deducted from assets. It's a residual, which is why the equation is often rearranged as Equity = Assets − Liabilities. For a sole trader it's usually called capital; for a company it's share capital plus retained earnings and other reserves.
Equity isn't a pile of cash. A business with large equity may have very little cash if its resources are tied up in equipment and inventory.
The expanded equation
Equity changes for four reasons, so the equation is often written in an expanded form:
Assets = Liabilities + Owner's capital + Revenue − Expenses − Drawings
(For a company, read "share capital" for capital and "dividends" for drawings.)
- Contributions from owners increase equity.
- Revenue increases equity: the business has earned something.
- Expenses reduce equity: resources have been used up to earn revenue.
- Drawings or dividends reduce equity: resources go back to the owners. They are not expenses, because they aren't incurred to earn revenue.
Revenue minus expenses is profit, so in a sentence: closing equity = opening equity + new capital + profit − distributions. That link is exactly how the income statement connects to the statement of financial position, as the guide on how the financial statements connect shows.
The four ways a transaction can move the equation
Every transaction does one of these, or a combination:
- Both sides up — an asset increases and a liability or equity increases by the same amount (borrowing cash; earning revenue on credit).
- Both sides down — an asset decreases and a liability or equity decreases (paying a supplier; paying an expense in cash).
- Swap within assets — one asset up, another down (buying equipment for cash; collecting a receivable).
- Swap within the right-hand side — one liability or equity item up, another down (converting a loan into shares; accruing an expense against a liability, where the expense reduces equity and the liability rises).
If you can say which of the four a transaction is, you can record it.
A worked example: Fennick Bike Repairs
Ola Fennick opens a bike repair workshop. Here is the first month, transaction by transaction. A = assets, L = liabilities, E = equity.
- Ola puts 20,000 of her own money into the business bank account. Cash +20,000; capital +20,000. Both sides up.
- The business borrows 10,000 from the bank. Cash +10,000; bank loan +10,000. Both sides up.
- It buys tools and a workstand for 6,000 cash. Equipment +6,000; cash −6,000. A swap within assets — total assets unchanged.
- It buys spare parts for 2,500 on 30-day credit. Parts inventory +2,500; accounts payable +2,500.
- It completes repairs worth 4,200: customers pay 3,000 at collection and a cycling club owes 1,200 on account. Cash +3,000; receivables +1,200; revenue (equity) +4,200.
- It pays the month's rent of 1,100. Cash −1,100; rent expense reduces equity by 1,100.
- It pays the parts supplier 1,500 of the 2,500 owed. Cash −1,500; accounts payable −1,500.
- Ola takes 800 for personal use. Cash −800; drawings reduce equity by 800.
- The cycling club pays 700 of what it owes. Cash +700; receivables −700. A swap within assets.
| After transaction | Assets | Liabilities | Equity |
|---|---|---|---|
| 1. Owner invests | 20,000 | 0 | 20,000 |
| 2. Bank loan | 30,000 | 10,000 | 20,000 |
| 3. Buy tools for cash | 30,000 | 10,000 | 20,000 |
| 4. Parts on credit | 32,500 | 12,500 | 20,000 |
| 5. Repairs earned | 36,700 | 12,500 | 24,200 |
| 6. Pay rent | 35,600 | 12,500 | 23,100 |
| 7. Pay supplier | 34,100 | 11,000 | 23,100 |
| 8. Owner's drawings | 33,300 | 11,000 | 22,300 |
| 9. Customer pays | 33,300 | 11,000 | 22,300 |
At every row, assets equal liabilities plus equity. At the month-end the detail is:
| Element | Detail | Amount |
|---|---|---|
| Cash | 20,000 + 10,000 − 6,000 + 3,000 − 1,100 − 1,500 − 800 + 700 | 24,300 |
| Receivables | 1,200 − 700 | 500 |
| Parts inventory | 2,500 | |
| Equipment | 6,000 | |
| Total assets | 33,300 | |
| Accounts payable | 2,500 − 1,500 | 1,000 |
| Bank loan | 10,000 | |
| Total liabilities | 11,000 | |
| Capital | 20,000 | |
| Profit for the month | revenue 4,200 − rent 1,100 | 3,100 |
| Drawings | (800) | |
| Total equity | 22,300 |
Liabilities 11,000 + equity 22,300 = 33,300 = total assets. Notice three things. Profit was 3,100 but cash rose by 24,300 because most of the cash came from Ola and the bank, not from trading. Drawings reduced equity but are not in the profit figure. And collecting the 700 changed nothing on the right-hand side, because the revenue was already recorded in transaction 5.
To try this yourself with your own transactions, use the accounting equation simulator — it shows the three totals moving as you post.
From the equation to debits and credits
Assets sit on the left of the equation, so assets increase on the left side of an account — a debit. Liabilities and equity sit on the right, so they increase with a credit. Expenses and drawings reduce equity, so they are recorded as debits; revenue increases equity, so it's a credit. Every journal entry has equal debits and credits for the same reason the equation always balances. The debits and credits guide takes this further.
Common mistakes
- Treating owner contributions as revenue. Money the owner puts in increases capital, not revenue. It wasn't earned from customers.
- Treating drawings or dividends as expenses. They reduce equity directly and never appear in profit.
- Recording revenue again when cash is collected. Collecting a receivable is a swap within assets; the revenue was recorded when the work was done.
- Recording an expense when a supplier is paid. If the bill was already recorded in accounts payable, paying it reduces cash and the liability — no new expense.
- Thinking equity is cash. Equity is a claim on all the assets, not a bank balance.
- Recording events that aren't transactions. Signing a contract to buy equipment next month, or hiring an employee who starts next week, doesn't change assets, liabilities or equity yet. The lesson on transactions and economic events covers where the line is.
Frequently asked questions
Can the accounting equation ever not balance?
Not if every transaction is recorded with equal debits and credits. If your totals disagree, an entry has been recorded one-sided or with unequal amounts — which is exactly what a trial balance is designed to catch.
Can equity be negative?
Yes. If liabilities exceed assets — for example after years of losses — equity is negative. The equation still balances: assets = liabilities + (a negative) equity.
Where does profit go?
Profit for the period increases equity. In a company it is added to retained earnings, less any dividends declared. That's why the income statement and the statement of financial position are linked.
Practise it
The accounting equation lesson has graded impact and numeric questions, and it's free. When you're ready to keep a real set of books, the Your First Day case runs a design studio's first month from source documents. Complete beginners can follow the whole free route in the Start from zero pathway.