What You'll Learn
By the end of this lesson, you'll understand:
- What assets, liabilities, and equity are
- How the accounting equation stays in balance
- How everyday business events change the equation
- Why buying an asset with cash does not make a business poorer
- Why borrowing increases both assets and liabilities
- How revenue and expenses affect equity
The Big Idea
Imagine a business as a box. Inside the box are things the business owns. Outside the box are two groups of people who have a claim on those things: the people the business owes (lenders and suppliers), and the owner.
Everything inside the box must be claimed by someone. So the value of what's inside always equals the value of the claims on it. That is the accounting equation:
Assets = Liabilities + Equity
Read it out loud: what the business owns equals what it owes plus what belongs to the owner. This single sentence is the foundation of every bookkeeping record you will ever make.
The Three Parts of the Equation
Assets
Things the business owns that have value. Cash, equipment, supplies, money customers owe you, and inventory are all assets. If the business could use it or sell it, it's an asset.
Liabilities
Money the business owes to someone else. Unpaid bills, bank loans, and credit card balances are liabilities. A liability is a promise to pay later.
Equity
What belongs to the owner after all debts are paid. It starts with the owner's investment and grows when the business earns revenue. It shrinks when the business pays expenses or the owner takes money out.
Why the Equation Must Stay Balanced
The equation balances because every transaction touches at least two things. If cash goes up, something else must change too — either a liability goes up (you borrowed it), an asset goes down (you traded it), or equity goes up (you earned it).
You cannot make just one side move by itself. That is why bookkeepers always record both sides of a transaction. When the books are done right, the equation balances every single time.
Following a Small Business
Let's follow a new business through six events. For each one, we'll ask "What happened in the business?" first, then look at how the equation changes. We are not using debits and credits yet — that comes later. For now, we just watch the equation.
Event 1 — The owner invests $10,000
What happened in the business?
The owner opens a new business and deposits $10,000 of personal money into the business checking account.
| Assets | Liabilities | Equity |
|---|---|---|
| — |
|
| $10,000 | $0 | $10,000 |
Cash (an asset) goes up by $10,000. Owner's Capital (equity) goes up by the same amount. The equation balances: $10,000 = $0 + $10,000.
Event 2 — Buy equipment with cash
What happened in the business?
The business buys $3,000 worth of equipment and pays for it in cash.
| Assets | Liabilities | Equity |
|---|---|---|
| — |
|
| $10,000 | $0 | $10,000 |
Cash drops by $3,000, but Equipment rises by $3,000. Total assets stay the same. Nothing is owed, so liabilities and equity do not change. The business traded one asset for another — it is not poorer.
Event 3 — Buy supplies and agree to pay later
What happened in the business?
The business buys $2,000 of supplies but does not pay yet. The supplier sends a bill due in 30 days.
| Assets | Liabilities | Equity |
|---|---|---|
|
|
|
| $12,000 | $2,000 | $10,000 |
Supplies (an asset) go up by $2,000. Accounts Payable (a liability) goes up by $2,000. The equation balances: $12,000 = $2,000 + $10,000.
Event 4 — Borrow money from the bank
What happened in the business?
The business borrows $5,000 from the bank and deposits it into checking.
| Assets | Liabilities | Equity |
|---|---|---|
|
|
|
| $17,000 | $7,000 | $10,000 |
Cash goes up by $5,000. Loan Payable (a liability) goes up by $5,000. Both sides grow equally. The business has more cash, but it also owes more.
Event 5 — Earn revenue and receive cash
What happened in the business?
The business does work for a customer and receives $1,500 in cash.
| Assets | Liabilities | Equity |
|---|---|---|
|
|
|
| $18,500 | $7,000 | $11,500 |
Cash goes up by $1,500. Revenue increases equity by $1,500. Earning money makes the business more valuable to its owner.
Event 6 — Pay an expense in cash
What happened in the business?
The business pays $500 cash for rent for the month.
| Assets | Liabilities | Equity |
|---|---|---|
|
|
|
| $18,000 | $7,000 | $11,000 |
Cash drops by $500. Expenses reduce equity by $500. Spending money to run the business makes the owner's share smaller.
Key Ideas From the Example
Buying an asset with cash does not make the business poorer. Cash goes down, but a new asset goes up by the same amount. Total assets stay the same. You traded one form of value for another.
Borrowing money increases both assets and liabilities. The cash coming in is an asset. The promise to repay is a liability. Both sides grow equally, so the equation stays balanced. The business is not richer — it just holds more cash that it owes.
Earning revenue increases equity. When the business earns money, the owner's share grows. Assets go up (more cash) and equity goes up (more revenue) by the same amount.
Paying an expense decreases equity. When the business spends money to operate, the owner's share shrinks. Assets go down (less cash) and equity goes down (an expense) by the same amount.
Try It
Read each business event. Then choose what happens to the accounting equation — which parts increase, decrease, or stay the same. After you answer, read why.
Exercise 1
The business borrows $5,000 from the bank and deposits the money into its checking account.
What happens to the accounting equation?
Exercise 2
The business buys a $2,000 computer and pays for it in cash.
What happens to the accounting equation?
Exercise 3
The business does work for a customer and receives $800 in cash.
What happens to the accounting equation?
Check Your Understanding
Answer each question, then read the explanation. There's no score — this is just to help the ideas stick.
Question 1
A business buys a $1,500 laptop and pays cash. What happens to the equation?
Question 2
The business borrows $3,000 from the bank. Why do both assets and liabilities increase?
Question 3
The business pays $200 cash for utilities. How does this affect equity?
Key Takeaways
- The accounting equation is Assets = Liabilities + Equity. It is always true.
- Assets are what the business owns. Liabilities are what it owes. Equity is what belongs to the owner.
- Every transaction changes at least two things, so the equation always stays balanced.
- Buying an asset with cash keeps total assets the same — you traded one asset for another.
- Borrowing increases both assets (cash) and liabilities (the loan) by the same amount.
- Revenue increases equity. Expenses decrease equity.