amazon.co.ukA* revision of the double entry model for AQA 7127 (3.3-3.4): debits and credits, books of prime entry, trial balance, suspense accounts, control accounts and bank reconciliation, with exam-style error correction and the benefits and costs of the double entry system.
Every transaction has a dual effect: it changes at least two items, and the accounting equation survives each change. If Suneja opens a business with £20,000 from savings, assets (bank) rise £20,000 and capital rises £20,000. If she then buys a van for £6,000 cash, one asset rises and another falls - the equation still balances. If she buys inventory for £2,000 on credit, assets rise £2,000 and liabilities (payables) rise £2,000. The equation is not a formula to memorise for one question: it is the logic that generates every debit and credit.
| Account category | To increase | To decrease |
|---|---|---|
| Assets (non-current and current) | Debit | Credit |
| Expenses (including purchases) | Debit | Credit |
| Drawings | Debit | Credit |
| Liabilities | Credit | Debit |
| Capital / equity | Credit | Debit |
| Income (sales, rent receivable, discount received) | Credit | Debit |
A four-step routine decides any entry. Step 1: identify the two (or more) accounts affected. Step 2: classify each as asset, liability, capital, income or expense. Step 3: decide whether each increases or decreases. Step 4: apply the table. Test it: pay wages £800 in cash. Wages (expense) increase, so debit wages £800; cash (asset) decreases, so credit cash £800. Receive £500 rent from a sub-tenant: debit bank (asset up), credit rent receivable (income up). Owner takes goods worth £150: debit drawings £150, credit purchases £150 - goods drawn are recorded at cost, credited to purchases, not sales.
| Transaction | Debit | Credit |
|---|---|---|
| Buy goods on credit from Pell Ltd £2,400 | Purchases 2,400 | Pell Ltd 2,400 |
| Sell goods on credit to Kaur £3,100 (cost £1,900) | Kaur 3,100 | Sales 3,100 |
| Return goods to Pell £180 | Pell Ltd 180 | Purchases returns 180 |
| Kaur pays £3,100 by cheque | Bank 3,100 | Kaur 3,100 |
| Pay Pell £2,220 in full settlement of £2,400, taking discount | Pell Ltd 2,400 | Bank 2,220; Discount received 180 |
| Owner pays in a second £5,000 | Bank 5,000 | Capital 5,000 |
| Buy shelving by cheque £1,500 | Equipment 1,500 | Bank 1,500 |
| Pay rent by standing order £600 | Rent payable 600 | Bank 600 |
The Pell settlement shows the settlement discount rule: only the discount actually taken is recorded, split so the payables account is cleared in full. A trade discount, by contrast, would simply mean the purchases were recorded at, say, £2,280 rather than list price.
Transactions are first entered in a book of prime entry, which keeps the ledger clean, records supporting details once, and creates an audit trail. The sales day book lists credit sales invoices (total posted to debit sales, each invoice posted to the credit of the individual customer). The purchases day book does the mirror image for credit purchases. Returns inwards and returns outwards books handle credit notes and debit notes. The cash book records all bank and cash movements and is both a book of prime entry and a ledger account, often extended with discount allowed and discount received columns. The petty cash book records small cash payments under analysed heads, using the imprest system: the float is topped up to a fixed amount by the exact value of vouchers, so the petty cashier is automatically checked. The general journal records everything else: opening entries, purchases and sales of non-current assets on credit, corrections of errors, irrecoverable debts written off, and the year-end transfer entries.
The ledger is split for control: the sales (receivables) ledger holds one account per credit customer, the purchases (payables) ledger one per supplier, and the nominal (general) ledger everything else, including the sales ledger control and purchases ledger control accounts. Every posting carries a folio reference (e.g. SL 14, CB 7) cross-referencing book to account. Folios look cosmetic but they are examinable: they prove each entry was cross-checked, they let any figure be traced both ways, and they are part of the internal control story you must be able to tell in extended answers about the benefits and costs of the double entry system (3.1, 3.3). The costs are real: a full double entry system needs trained staff, books or software, and time; for a micro-business with few transactions the cost can exceed the benefit, which is why incomplete records techniques exist (3.14).
Command-word discipline matters here. For state or identify, give the entry only. For explain, give the entry and why (account classification plus the dual effect). For prepare the journal entries, show date, accounts, amounts, and a narration - AQA mark schemes award for narrations because they demonstrate the transaction, not the habit, has been understood.
Push the dual effect one step further, because examiners love the cases where the equation survives something that looks one-sided. A customer pays £1,200 in December for work to be done in January: bank (asset) rises, but the credit is to deferred income (revenue received in advance) - a liability - because no income has been earned yet. The business receives an electricity bill for £300 but will pay next month: the expense is debited now and the credit sits in accruals, a liability. In both cases the equation holds because a liability absorbs the difference. Candidates who credit sales or debit expenses directly have destroyed the matching that the ledger is supposed to preserve, and the error surfaces in the adjustments section of Paper 1. Similarly, when a non-current asset is bought partly on credit, the debit is the asset but the credits split between bank and the supplier's personal account - two credits against one debit is perfectly valid double entry, since 'two entries' means at least two, not exactly two.
Ridge sells goods list price £1,000 to Doherty, allowing 10% trade discount and offering 2.5% settlement discount. Invoice raised: £1,000 less 10% = £900. Entry: Dr Doherty £900, Cr Sales £900 - the trade discount is buried in the figure and never appears separately. If Doherty pays within terms, the settlement discount is £22.50 (2.5% of £900): Dr Bank £877.50, Dr Discount allowed £22.50, Cr Doherty £900. Ridge's books show discount allowed £22.50 (expense). From Doherty's side the mirror image: Dr Ridge £900, Cr Bank £877.50, Cr Discount received £22.50 (income). If Doherty pays late, nothing further is recorded - settlement discounts are recognised only when taken, unlike trade discounts which are recognised by never recording them.
Posting runs in totals with only the personal accounts getting individual attention. If the sales day book for March lists 40 invoices totalling £46,300, the nominal ledger receives one entry - Dr Sales ledger control £46,300, Cr Sales £46,300, folios referencing SDB 3 and NL 22 - while each of the 40 customers' personal accounts is credited with its own invoice amount. This is why the sales ledger control account in section 3 below can be rebuilt from the day books alone: the control account receives exactly the same totals the day book produced. Understanding this flow answers a classic exam question - state the source of each entry in a control account - and stops candidates inventing entries (such as irrecoverable debts written off) that never pass through the day books but only through the journal.
Multiple-choice and short-answer items on 3.3 are usually one-line decisions - state the double entry for paying a supplier by standing order (Dr payables, Cr bank) - so speed comes from classification, not memory. The extended questions reward narrative control: knowing that the cash book doubles as a ledger account, that the journal is the book of corrections, and that every figure in the financial statements can be traced through folio references back to a source document. Hold the whole chain in mind - source document, book of prime entry, ledger, trial balance, financial statements - because every later topic in the specification (adjustments in 3.6, company accounts in 3.16, even the data trail questions on technology) assumes you can move along it in either direction without hesitation.
At the reporting date each ledger account is balanced: total both sides, insert the smaller total as balance c/d on the larger side, carry it down as balance b/d on the opposite side. Debit balances (assets, expenses, drawings) and credit balances (liabilities, capital, income) are then listed in a trial balance. Because every transaction was recorded with equal debits and credits, the two columns must agree. If they do not, something is wrong - and the difference is parked in a suspense account so final accounts can be drafted while the error is traced. Suspense is a device, not an account with meaning: a trial balance must agree, and the suspense account must be cleared, before financial statements are finalised.
The crucial A* distinction is between the six error types a balanced trial balance cannot detect and the errors it can. All six undetectable types are balanced errors: both sides were recorded, just wrongly.
| Error type | Example | Revealed by TB? |
|---|---|---|
| Complete omission | A £400 credit sale never recorded at all | No |
| Same wrong amount both sides | Sale recorded as £540 instead of £450 in both accounts | No |
| Error of commission | Debited the wrong customer's account | No |
| Error of principle | Motor expenses debited to motor vehicles | No |
| Reversal of entries | Sale debited to sales, credited to customer | No |
| Compensating errors | Sales overcast £100, wages overcast £100 | No |
| One-sided errors (posting one side only; casting one account wrongly) | Cash debited, receivables never credited | Yes - TB fails |
So a trial balance that agrees is not evidence that the records are correct: any of the six balanced errors could be sitting inside it. That is why verification continues beyond the trial balance with control accounts, bank reconciliation and physical checks (3.4). Conversely, a trial balance that fails tells you a one-sided error exists but not which - hence the suspense account.
Balancing itself is examinable. In the wages account for a month, total debits (wages paid) sit on the left; the balance c/d goes to the right at the period end, and comes back as balance b/d ready to start the next period. Accumulate it over the year and the closing balance transfers to the statement of profit or loss. Permanent accounts (assets, liabilities, capital) carry their balances forward as balance b/d into the next period and appear in the statement of financial position; temporary accounts (income and expenses) are closed off to the statement of profit or loss and start each new period at nil. Knowing which accounts are which tells you instantly where a balance belongs in the final accounts - and it explains why drawings is a debit-balance account deducted from capital rather than an expense.
When the trial balance disagrees, open the suspense account with the difference on the side that is short. If debits exceed credits by £100, suspense carries a debit balance of £100, restoring apparent agreement. Then correct each error through the journal. For each correction ask two questions. First, does this error involve an account missing an entry on one side only (or a wrong amount on one side)? If yes, the suspense account absorbs the imbalance. Second, do the correcting entries touch income or expense accounts? If yes, profit for the year changes.
A business's trial balance shows debits £96,000 and credits £95,900, a difference of £100. The suspense account is opened with a debit balance of £100. Three errors are then found:
Net effect on profit: +£400 − £600 = −£200. Note the pattern examiners reward: the correction that used the suspense account (error 1) changed no profit figure, because suspense entries are always equal debits and credits by construction. Profit effects come only from balanced errors corrected through the statement of profit or loss accounts. Also state the balance sheet effects: trade receivables were overstated by £100, motor vehicles overstated by £600 before correction.
Common one-sided errors to watch for in data: a casting error in a single account (e.g. sales day book totalled £9,860 instead of £8,960, posted as £9,860); a posting made to one side of one account only; two debits with no credit; the wrong figure on one side. Common balanced errors that trap candidates: writing off an irrecoverable debt but crediting the customer's account and forgetting the receivables control account interplay, or treating drawings of goods as at selling price (it is at cost, credited to purchases). Reversals (type 4) are corrected by doubling the wrong entry: if a £250 receipt was reversed, debit and credit the original accounts again with £250 to cancel, then post correctly - a two-step journal worth stating explicitly for full marks.
Remember the statement of financial position consequences as well as the profit consequences, because part (b) of these questions almost always asks for both. An uncorrected error of principle (expenses sitting in motor vehicles) overstates both profit and non-current assets; an uncorrected omission of a credit sale understates profit, trade receivables and revenue. And a suspense account must be cleared before the financial statements are published: a suspense balance in a published statement of financial position signals uncorrected records and would prevent the accounts from showing a true and fair view. In exam answers, finish every suspense question by writing 'the suspense account now has a nil balance' - it is a marking point in its own right.
For the extended-answer variant - discuss whether a trial balance that agrees proves the accounts are accurate - structure as: (i) purpose of the trial balance (arithmetic check of double entry); (ii) the six undetectable error types with one example each; (iii) what does provide assurance (control accounts reconciled, bank reconciliation, physical stock counts, internal check segregation); (iv) judgement that a balanced TB is necessary but far from sufficient. That fourth move - the justified conclusion - is what separates the top band from mid band in AQA's 25-mark Section C questions.
Petty cash float £200, restored by imprest. During the week vouchers totalled £87 (postage £34, cleaning £28, stationery £25). The cashier reimburses exactly £87, restoring the float to £200. Check: float £200 = vouchers £87 + cash in box £113. The verification is built in - if cash plus vouchers does not equal the imprest amount, something is missing, and the analysis columns feed the nominal accounts (Dr postage, Dr cleaning, Dr stationery, Cr cash) without cluttering the main cash book.
Finally, link the model to the accountant's role (3.1). Double entry is not paperwork for its own sake: it is what allows the trial balance to self-check the books, the financial statements to be prepared from ledger balances rather than reconstructed by guesswork, and managers to interrogate any figure back to its source document. When you are asked to evaluate the double entry system, anchor each benefit to this mechanism and each cost to the resources it consumes - that is the difference between assertion and analysis.
Verification goes beyond the trial balance. The three named mechanisms in 3.4 are control accounts, the bank reconciliation and checks on the personal ledgers. Their shared logic: build a figure independently from summary records, then compare it with the detailed records. Any difference must be explained and corrected. In an exam this is one of the highest-yield preparation areas because the formats are fixed and the marks are mechanical.
A sales ledger control account summarises everything owed by credit customers; the purchases ledger control account summarises everything owed to suppliers. Critical rule: build them only from the day books, returns books and cash book - never from the individual personal accounts - otherwise the check is circular. Items are posted in totals, with the other side of each entry to the nominal account named in brackets.
| Dr side (sales ledger control) | Source | Cr side | Source |
|---|---|---|---|
| Opening balance b/d | Last year's TB | Cash and cheques received | Cash book (Cr bank) |
| Credit sales | Sales day book (Cr sales) | Discounts allowed | Cash book (Dr discount allowed) |
| Dishonoured cheques | Bank statement (Cr bank) | Returns inwards | Returns inwards book (Dr returns inwards) |
| Interest charged on overdue accounts | Journal (Cr interest income) | Irrecoverable debts written off | Journal (Dr irrecoverable debts) |
| Contra to purchases ledger | Journal (Dr purchases ledger control) | ||
| Closing balance c/d | Balance figure |
The purchases ledger control is the mirror image: debits for payments, discounts received, returns outwards and contras; credits for opening balances and credit purchases. A contra (set-off) arises where the business is both customer and supplier of the same firm: the two balances are netted, Dr Purchases ledger control, Cr Sales ledger control, with no cash movement. Reconciling the control account to the list of personal balances: prepare the control account, list and total the individual balances, then investigate the difference. Typical causes: a transaction omitted from the list of balances but in the control account (or vice versa); a casting error in either; a posting to the wrong personal account (commission - affects the list total, not the control account); or an error in the control account itself. Explain each difference, correct it, and show that both now agree.
Control accounts deliver control benefits you should be able to evaluate for AO3: they localise errors (the discrepancy is inside one ledger, not the whole system); they deter fraud because a different clerk maintains the personal ledgers from the one who prepares the control account (internal check through segregation of duties); they give the trial balance a quick receivables/payables figure; and for large businesses they allow the sales ledger to be split across clerks without losing overall control. The cost is duplication of bookkeeping work and the need for competent, independent staff.
The bank reconciliation follows the same compare-and-explain logic between the cash book and the bank statement. Always in this order. Step 1: update the cash book for items on the statement not yet in the books - bank charges and interest, standing orders and direct debits, direct credits (customers paying directly), dishonoured cheques, and any bank errors. The corrected cash book balance is the figure that appears in the statement of financial position. Step 2: list timing differences, which need no entry: cheques paid in but not yet credited (outstanding lodgements) and cheques issued but not yet presented. Step 3: start from the updated cash book balance and adjust for timing, or start from the statement balance and work back - both must land on the same number.
Cash book shows a debit balance of £4,320. The bank statement shows £4,880. The statement reveals bank charges £50, a direct credit from a customer of £200, unpresented cheques £1,150, and a lodgement of £740 not yet credited.
| Updated cash book | £ |
|---|---|
| Balance per cash book (Dr) | 4,320 |
| Less: bank charges | (50) |
| Add: direct credit | 200 |
| Corrected (adjusted) balance | 4,470 |
| Reconciliation to statement | £ |
|---|---|
| Balance per bank statement | 4,880 |
| Less: unpresented cheques | (1,150) |
| Add: outstanding lodgement | 740 |
| Balance per updated cash book | 4,470 |
Mark-scheme pattern: the £50 and £200 go through the cash book with double entries (Dr/Cr bank); the £1,150 and £740 appear in no ledger account at all - they are pure timing. Candidates who 'correct' the cash book for unpresented cheques throw marks away every year.
Two reconciliation wrinkles appear regularly. A dishonoured cheque from a customer (insufficient funds, or a technical error) reverses the original receipt: Dr Trade receivables, Cr Bank - the customer owes again, so it appears on the debit side of the sales ledger control account and the customer's personal account. A bank error (for example the bank debiting your account with another customer's direct debit) is corrected by notifying the bank; it appears only in the reconciliation statement, never in your books, until the bank corrects it. Remember too that the figure reported in the statement of financial position is the corrected cash book balance - if that is negative, the overdraft is a current liability.
The purchases ledger control account is the exact mirror image, and being able to state its sources is a standard short-answer demand.
| Dr side (purchases ledger control) | Source | Cr side | Source |
|---|---|---|---|
| Payments to suppliers | Cash book (Cr bank) | Opening balance b/d | Last year's TB |
| Discounts received | Cash book (Cr discount received) | Credit purchases | Purchases day book (Dr purchases) |
| Returns outwards | Returns outwards book (Dr returns outwards) | ||
| Contra to sales ledger control | Journal | ||
| Closing balance c/d | Balance figure |
To reconcile either control account with its list of balances: prepare the control account from the summary books; list and total the individual balances from the memorandum ledger; then explain and correct any difference line by line. Typical causes, each with its correcting treatment: a transaction in the control account but omitted from the list (add it to the list); a casting error in one personal account (correct that account); a posting to the wrong personal account - an error of commission - which distorts the list total but not the control account (transfer the amount between the two personal accounts); an entry missing from the control account itself (post it); or a debit balance among the payables (an advance payment) listed as a negative. The discipline of explaining each difference, not just adjusting, is what the mark scheme pays for.
Tie it together for the extended question on the benefits and costs of operating a double entry bookkeeping system (3.3, with links to 3.1). Benefits: it self-checks (trial balance), it detects errors and deters fraud through control accounts and reconciliation, it produces reliable financial statements and management information for decisions, it supports tax compliance and audit, and it permits performance comparison over time. Costs: staffing and training; software purchase and maintenance; data security investment; time taken per transaction; risk that over-complex systems generate information nobody uses. The evaluation point AQA rewards: the benefits grow with the size and complexity of the business, so the optimal system differs between a market trader (incomplete records may suffice) and a limited company (full double entry is legally required). Conclude with a judgement, not a list.
In Paper 1 this material typically appears as a 20-mark structured question (prepare a control account, then reconcile, then explain one cause of difference) or inside a Section C scenario asking you to evaluate internal control. Whatever the wrapper, the mechanics are identical: know the source of every control account line, know which items enter the cash book and which are pure timing, and be ready to state double entries for the adjustments (dishonoured cheque, contra, write-off). Drill the formats until you can produce a balanced control account in under five minutes - the time saved funds the evaluation paragraphs that decide the top grades.