Last reviewed: July 2026.
Incomplete Records: Mark-Up, Margin and Missing Figures is a practical guide designed to connect current accounting requirements with clear preparation steps, calculations and review controls.
Why incomplete-records calculations are necessary
Incomplete records arise when a business lacks a complete double-entry system or when documents and ledgers are missing. The accountant must reconstruct sales, purchases, expenses, assets and liabilities from the evidence that remains. The process is not guesswork: every amount should be derived from a relationship, control account, cash record, inventory movement or capital comparison and then tested for consistency.
Start with a document and evidence map
List the records available: bank statements, cash books, invoices, supplier statements, inventory counts, payroll records, tax returns, loan statements and owner records. Note the period each document covers and whether it is complete. An evidence map prevents one transaction being counted twice and identifies where estimates or alternative calculations are required.
Mark-up and margin formulas
Mark-up expresses gross profit as a percentage of cost, while margin expresses gross profit as a percentage of sales. If cost is 80 and sales are 100, gross profit is 20, mark-up is 25% and margin is 20%. To convert mark-up to margin, divide the mark-up percentage by 100 plus the mark-up percentage. To convert margin to mark-up, divide the margin percentage by 100 minus the margin percentage.
Reconstructing sales from gross profit
When cost of sales and a stable gross-profit rate are known, sales can be reconstructed. Suppose opening inventory is 25,000, purchases are 140,000 and closing inventory is 35,000. Cost of sales is 130,000. If the business applies a 30% mark-up on cost, gross profit is 39,000 and estimated sales are 169,000. The rate should be supported by price lists, prior periods or product-level evidence.
Reconstructing credit sales
A receivables control account can derive credit sales. Start with opening receivables, add credit sales, and deduct cash received, sales returns, discounts, bad debts and other credits to arrive at closing receivables. Rearranging the account gives the missing sales figure. Separate cash sales because they do not pass through trade receivables.
Reconstructing credit purchases
A payables control account can derive credit purchases. Begin with opening payables, add credit purchases, and deduct supplier payments, purchase returns, discounts received and other debits to arrive at closing payables. Supplier statements and bank payments are important cross-checks. Cash purchases must be added separately when calculating total purchases.
Cash and bank reconstruction
Use bank statements to rebuild receipts and payments, but adjust for transfers, loans, capital introduced, drawings and non-trading transactions. Cash takings may be banked net of expenses or drawings, so bank deposits are not automatically equal to sales. A reconstructed cash account should explain opening cash, recorded receipts, payments and closing cash.
Capital comparison method
Profit may be estimated from the change in net assets after adjusting for owner transactions. Closing capital minus opening capital, plus drawings, minus additional capital introduced, gives profit when no other capital adjustments exist. This method provides a valuable cross-check but does not replace a properly reconstructed income statement because errors in asset or liability balances directly affect the result.
Worked missing-profit example
Assume opening capital is 90,000 and closing capital is 126,000. During the year the owner introduced 15,000 and withdrew 24,000. Profit is 45,000: closing capital 126,000 minus opening capital 90,000, plus drawings 24,000, minus capital introduced 15,000. The result should be compared with reconstructed gross profit and expenses.
Reasonableness and fraud checks
- Compare gross-profit rates with prior periods and industry evidence.
- Check whether reconstructed sales agree with tax and payment records.
- Investigate round-number estimates and unexplained cash withdrawals.
- Confirm closing receivables and payables with third-party statements.
- Document assumptions and retain alternative calculations.
Using inventory equations
The inventory equation is opening inventory plus purchases minus closing inventory equals cost of sales, adjusted for returns, carriage and abnormal losses where relevant. If three components are known, the fourth can be derived. However, inventory counts must be tested for ownership, cut-off and valuation. A mathematically balanced equation can still be wrong if goods held on consignment or obsolete items are included incorrectly.
Estimating expenses and accruals
Expenses may be reconstructed from payments after adjusting opening and closing accruals or prepayments. For example, expense equals cash paid plus closing accrual minus opening accrual plus opening prepayment minus closing prepayment. Loan statements can separate interest from principal. Payroll returns, utility bills and rental agreements provide independent support for recurring expenses.
Documenting uncertainty
Where exact reconstruction is impossible, disclose the basis of estimation, source evidence, sensitivity and reviewer conclusion. Use the most reliable evidence first and avoid creating false precision. A range may be more honest than a single unsupported number during an investigation, although final statutory accounts normally require a best estimate supported by available information.
Final reconstruction review
Before finalising the accounts, compare the reconstructed profit with cash generation, owner drawings, tax records and changes in net assets. Resolve material differences rather than averaging competing answers. The final file should show the formula, source evidence, assumption and reviewer conclusion for every reconstructed amount.
Related Accounting Support guides
Use the incomplete records overview, the reconstruction steps guide and the cash-book reconstruction guide as a connected learning path.
Authoritative references
See ACCA’s Incomplete records guidance and the official Business records if you are self-employed requirements.