The accounting equation and double entry

Accounting records and communicates financial information about an identifiable entity. The business entity concept separates the business's records from the personal finances of its owner. If an owner pays a private household bill from business cash, the transaction is usually recorded as drawings in a sole trader's books, not as an ordinary business expense. Keeping this distinction helps users measure business performance fairly.

The basic accounting equation is assets = liabilities + owner's equity. Assets are resources controlled by the business from which economic benefits are expected. Liabilities are present obligations to transfer resources. Owner's equity is the residual interest after liabilities are deducted from assets. Capital introduced by the owner increases equity; drawings reduce it. Profit also increases equity, while a loss reduces it.

Every recorded transaction has at least two effects that keep the equation balanced. If an owner introduces ₦80,000 cash, cash and capital both increase by ₦80,000. If the business then buys equipment for ₦30,000 cash, equipment increases and cash decreases by the same amount. Total assets do not change in that second transaction. If equipment is bought on credit instead, an asset and a liability both increase.

Double entry records equal total debits and credits. An increase in an asset or expense is normally debited. An increase in a liability, capital or income is normally credited. Decreases are recorded on the opposite side. Drawings normally have a debit balance because they reduce the owner's equity. Debit does not simply mean money received, and credit does not simply mean money paid: those shortcuts fail outside a narrow cash-account context.

Distinguish a capital expenditure, such as buying equipment for continuing use, from a revenue expense, such as rent for the current period. Classification depends on the nature and benefit of the expenditure rather than its size alone. Before making entries, identify the accounts affected, decide whether each increases or decreases, and then apply the debit and credit rules. Finally, check both the arithmetic equality and the economic meaning. A balanced entry can still be wrong if an inappropriate account has been used.

Follow the transaction before choosing a side

The debit and credit rules become easier when each transaction is analysed economically first. Ask which entity is recording it, what resource or obligation changes, and whether an income or expense belongs to this period. Only then choose the account and side. If a trader buys a delivery bicycle for cash, the bicycle asset rises and cash falls. If the trader buys it on credit, the bicycle asset rises and the amount owed to the supplier rises. The same physical purchase therefore produces different entries according to how it is financed.

A ledger account has a debit side and a credit side. Debit means the left side and credit the right side; neither word is inherently favourable or unfavourable. Assets, expenses and drawings normally increase on the debit side. Liabilities, capital and income normally increase on the credit side. Decreases go on the opposite side. A debit to cash records an increase in cash, but a debit to a payable records a reduction in the amount owed. Memorising debit as receipt fails immediately in that second case.

Profit and drawings within the equation

For a sole trader, closing capital can be expressed as opening capital plus additional capital plus profit minus drawings. A loss reduces capital instead of increasing it. Suppose opening capital is ₦150,000, the owner introduces ₦20,000, profit is ₦35,000 and drawings are ₦15,000. Closing capital is ₦190,000. The owner taking cash does not make the business earn less revenue or incur a business operating expense. It reduces the owner's residual claim. This distinction is essential when profit is later derived from changes in capital.

Income and expenditure also affect the equation. Earning service income on credit increases a receivable asset and income, which ultimately increases equity through profit. Paying an electricity expense decreases cash and decreases equity through the expense. Borrowing from a bank increases cash and a loan liability but does not create income. Repaying the principal reduces cash and the loan liability; interest is a separate expense when recognised under the stated basis. Separating principal from interest prevents a loan repayment from being treated entirely as an operating cost.

Recognise the accounting basis and inventory method

Under accrual accounting, income and expenses are recognised according to the relevant economic activity and period rather than only when money moves. A cash receipt from a customer can settle an existing receivable without creating new sales at that moment. A payment to a supplier can settle an existing payable without creating new purchases at that moment. Read whether a question says a credit transaction is being recorded for the first time or an old balance is being settled. Many double-entry mistakes begin with ignoring that difference.

Inventory entries depend on the system specified. In a simple periodic system, purchases of goods for resale are debited to Purchases and the closing inventory adjustment helps determine cost of sales. In a perpetual system, an inventory asset account is updated as goods move, with a separate cost-of-sales entry when goods are sold. A question should make its convention clear. Do not combine the purchases-account method with an unannounced perpetual inventory entry and then expect the trial balance to explain the inconsistency.

Concepts that support consistent records

The going-concern assumption normally treats the entity as continuing into the foreseeable future, rather than immediately selling everything in a forced closure. Consistency supports meaningful comparison of methods over time, while disclosure explains material changes. Prudence calls for caution in judgements under uncertainty, not deliberate understatement or hidden reserves. Materiality considers whether information could influence users'decisions. These ideas require judgement, but judgement must be supported by the transaction and accounting framework rather than used to excuse arbitrary figures.

Capital expenditure usually creates or improves a resource providing benefits beyond the current period. Revenue expenditure relates to the current operation or maintenance of earning capacity. Buying a machine differs from its routine servicing. A large payment is not automatically capital, and a small payment is not automatically revenue. The nature and purpose matter. Misclassifying a repair as an asset can overstate assets and profit; treating a productive asset purchase as an immediate expense can understate both in a simplified example.

Checks and self-assessment

After posting, confirm that total debits equal total credits, that the accounts match the transaction and that the resulting balances make economic sense. A bank loan credited to sales would preserve arithmetic equality but overstate income. Good narration briefly states what happened and links the entry to evidence such as an invoice or bank advice. Records should be sufficient for another person to follow the reasoning, without exposing unnecessary personal information.

Self-check: a business receives ₦50,000 borrowed from a bank. Debit Bank and credit Loan; revenue is unchanged. Self-check: a customer pays ₦12,000 already owed. Debit Bank or Cash and credit the customer's receivable; do not record the same sale again. Finally, explain why the accounting equation remains balanced in each case. Showing the two economic effects is a stronger demonstration of understanding than giving a correct side by guesswork.