📚 WJEC Year 12 Accounting Formula & Theorem Quick Reference Handbook | WJEC 12 年级会计公式定理速查手册
This handbook consolidates the essential formulas, rules, and concepts required for the WJEC Year 12 (AS) Accounting specification. It serves as a quick revision tool, enabling you to reinforce your understanding of financial and management accounting principles, double-entry rules, ratio analysis, and key decision-making models such as break-even and budgeting.
本手册汇总了 WJEC 12 年级（AS）会计大纲所必需的核心公式、规则与概念。作为快速复习工具，它将帮助你巩固对财务会计与管理会计原理、复式记账规则、比率分析以及盈亏平衡和预算等关键决策模型的理解。
1. The Accounting Equation | 会计等式
The accounting equation is the foundation of double-entry bookkeeping, expressing that a business’s assets are always financed by either liabilities or capital.
会计等式是复式记账的基础，表明企业的资产始终由负债或资本提供资金。
Assets = Capital + Liabilities
资产 = 资本 + 负债
Capital represents the owner’s claim on the assets after all liabilities have been settled (also known as equity or net worth): Capital = Assets − Liabilities.
资本代表清偿所有负债后所有者对资产的索取权（亦称权益或净值）：资本 = 资产 − 负债。
Every transaction has a dual effect, ensuring the equation remains in balance. For instance, purchasing inventory with cash increases one asset (inventory) and decreases another (cash), leaving total assets unchanged.
每笔交易都有双重影响，确保等式始终保持平衡。例如，用现金购买存货会增加一项资产（存货）同时减少另一项资产（现金），总资产不变。
The expanded accounting equation incorporates income and expenses: Assets = Capital + Liabilities + (Income − Expenses). This directly links to the preparation of financial statements.
扩展的会计等式纳入了收入与费用：资产 = 资本 + 负债 + (收入 − 费用)。这直接与财务报表的编制相联系。
2. Double-Entry Bookkeeping Rules | 复式记账规则
The double-entry system requires that every financial transaction affects at least two accounts, following the debit and credit rules for five main account types.
复式记账系统要求每笔财务交易至少影响两个账户，并遵循五类主要账户的借贷规则。
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Assets: increase with debit, decrease with credit.
资产：借方增加，贷方减少。
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Liabilities: increase with credit, decrease with debit.
负债：贷方增加，借方减少。
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Capital: increase with credit, decrease with debit.
资本：贷方增加，借方减少。
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Income (Revenue): increase with credit, decrease with debit.
收入（收益）：贷方增加，借方减少。
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Expenses: increase with debit, decrease with credit.
费用：借方增加，贷方减少。
For every transaction, total debits must equal total credits. For example, when a sale is made on credit, the customer account (asset) is debited and the sales account (income) is credited.
每笔交易中，借方总额必须等于贷方总额。例如，赊销商品时，客户账户（资产）记借方，销售收入账户（收入）记贷方。
Purchases and sales of inventory are recorded in separate accounts: purchases (expense) are debited, sales (income) are credited. Returns inwards reduce sales and are debited; returns outwards reduce purchases and are credited.
存货的购买和销售分别记录：购货（费用）记借方，销售收入（收益）记贷方。销售退回减少收入，记借方；购货退出减少费用，记贷方。
3. Trial Balance and Errors | 试算表与差错
A trial balance lists all ledger account balances at a given date, with debit and credit columns. Its purpose is to verify the arithmetic accuracy of the double-entry records.
试算表列出某日所有分类账账户的余额，分借方栏和贷方栏，其目的是验证复式记账记录的算术准确性。
A trial balance that balances does not guarantee the absence of all errors. Six types of error may not be detected: error of omission, error of commission, error of principle, compensating error, error of original entry, and complete reversal of entries.
试算表平衡并不能保证没有差错。六类差错可能无法被发现：漏记账、串户错误、原则性错误、抵销性错误、原始记录错误以及分录完全记反。
A suspense account is created temporarily to make the trial balance balance when errors prevent it from doing otherwise. Once the errors are found and corrected, the suspense account is cleared.
暂记账户是当错误导致试算表不能平衡时为使其平衡而暂时建立的账户。一旦找到并更正错误，暂记账户即被清空。
Correction of errors involves journal entries that follow the same double-entry rules. If a purchase of machinery was wrongly debited to purchases, the correction would be: debit machinery, credit purchases, and then record the necessary depreciation.
差错更正涉及遵循相同复式记账规则的日记账分录。如果购机器错误地记入购货账户借方，更正分录为：借机器设备，贷记购货，并记录必要的折旧。
4. Income Statement (Trading and Profit & Loss Account) | 损益表
The income statement calculates the profit or loss of a business over a specific period. It is divided into the trading account (gross profit) and the profit and loss account (net profit).
损益表计算企业特定期间的损益。它分为营业部分（毛利）和利润部分（净利润）。
Key formulas:
核心公式：
Cost of Sales = Opening inventory + Purchases + Carriage inwards − Purchase returns − Closing inventory.
销货成本 = 期初存货 + 购货 + 进货运费 − 购货退出 − 期末存货。
Gross Profit = Sales revenue − Sales returns (returns inwards) − Cost of Sales.
毛利 = 销售收入 − 销售退回 − 销货成本。
Net Profit = Gross Profit + Other income − Expenses.
净利润 = 毛利 + 其他收入 − 费用。
Expenses include wages, rent, insurance, depreciation, carriage outwards, advertising, bad debts, and provision for doubtful debts. Where prepayments and accruals exist, they must be adjusted to reflect the true expense for the period.
费用包括工资、租金、保险费、折旧、销货运费、广告费、坏账以及呆账准备。存在预付和应计项目时，必须进行调整以反映当期真实费用。
Net profit is transferred to the capital account in the statement of financial position.
净利润结转至资产负债表中的资本账户。
5. Statement of Financial Position (Balance Sheet) | 资产负债表
The statement of financial position shows the assets, liabilities, and capital of a business at a single point in time, confirming the accounting equation.
资产负债表显示企业在某一时点的资产、负债与资本，印证会计等式。
Non-current assets (fixed assets) are held for long-term use, such as land, buildings, machinery, and vehicles. They are recorded at cost less accumulated depreciation (carrying amount).
非流动资产（固定资产）为长期使用而持有，如土地、建筑物、机器和车辆。以成本减累计折旧（账面净值）列示。
Current assets are expected to be converted into cash within one year: inventory, trade receivables, prepayments, and cash/bank balances.
流动资产预计在一年内转化为现金：存货、应收账款、预付账款以及银行存款余额。
Current liabilities are obligations due within one year: trade payables, bank overdraft, and accruals. The difference between current assets and current liabilities is called net current assets (or working capital).
流动负债是一年内到期的债务：应付账款、银行透支和应计费用。流动资产减去流动负债的差额称为流动资产净值（或营运资金）。
Non-current liabilities are borrowings repayable after more than one year, such as long-term loans.
非流动负债是一年以上偿还的借款，如长期贷款。
Capital consists of opening capital plus additions of new capital and net profit, less drawings. The closing capital figure must equal total assets minus total liabilities.
资本由期初资本加上新增资本和净利润，减去提款构成。期末资本数必须等于总资产减总负债。
6. Depreciation Methods | 折旧方法
Depreciation is the systematic allocation of the cost of a non-current asset over its useful life, matching the expense to the periods benefiting from its use.
折旧是将非流动资产成本在其使用寿命内系统分配，使费用与受益期间相匹配。
Straight-line method (equal annual charge):
直线法（每年等额计提）：
Annual Depreciation = (Cost − Residual Value) ÷ Useful Life (years)
年折旧额 = (成本 − 残值) ÷ 使用年限
Reducing balance method (constant percentage applied to carrying amount each year):
余额递减法（每年按固定百分比对账面净值计提）：
Annual Depreciation = Carrying Amount × Depreciation Rate (%)
年折旧额 = 账面净值 × 折旧率(%)
The reducing balance method results in higher charges in early years. Whatever method chosen, the total depreciable amount equals cost less residual value, although reducing balance ignores residual value in formula unless capped.
余额递减法在早期产生较高折旧费。无论选用哪种方法，应计折旧总额等于成本减残值，尽管余额递减法在公式中通常忽略残值，除非设有下限。
Depreciation is recorded as an expense in the income statement and accumulated in a provision for depreciation account (contra-asset) on the statement of financial position. Disposal of assets requires removing the original cost and accumulated depreciation, and calculating any profit or loss on disposal.
折旧作为费用计入损益表，并在资产负债表中以累计折旧备抵账户（资产抵减）列示。资产处置时需冲销原始成本和累计折旧，并计算处置损益。
7. Inventory Valuation | 存货计价
Inventory must be valued at the lower of cost and net realisable value (NRV) to comply with the prudence concept. Cost includes purchase price, carriage inwards, and any other costs directly bringing inventory to its present location and condition.
存货必须按成本与可变现净值孰低原则计价，以满足谨慎性概念。成本包括购价、进货运费以及使存货达到当前位置和状态所直接发生的其他成本。
When specific identification is not possible, cost flow assumptions are used: First‑In, First‑Out (FIFO) and Average Cost (AVCO).
当无法具体辨认时，采用成本流转假设：先进先出法（FIFO）和平均成本法（AVCO）。
Under FIFO, the earliest purchases are assumed to be issued or sold first. Closing inventory is valued at the most recent purchase prices. During rising prices, FIFO gives a higher inventory valuation and higher profit.
FIFO 假设最早购入的存货最先发出或售出。期末存货按最近购价计价。在物价上涨时，FIFO 产生的存货价值较高，利润也较高。
Under AVCO, a weighted average cost per unit is recalculated after each purchase:
采用 AVCO 时，每次购货后重新计算加权平均单位成本：
Weighted Average Cost = Total Cost of Goods Available ÷ Total Units Available
加权平均成本 = 可供销售商品总成本 ÷ 可供销售商品总数量
AVCO smooths out price fluctuations. Both methods are acceptable under IAS 2, but must be applied consistently.
AVCO 平滑了价格波动。国际会计准则第 2 号允许使用两种方法，但必须一致应用。
8. Ratio Analysis: Profitability & Liquidity | 比率分析：盈利能力与流动性
Ratio analysis evaluates business performance and financial position. Key profitability ratios:
比率分析评价企业业绩和财务状况。核心盈利能力比率：
Gross Profit Margin = (Gross Profit ÷ Sales Revenue) × 100%
毛利率 = (毛利 ÷ 销售收入) × 100%
Net Profit Margin = (Net Profit ÷ Sales Revenue) × 100%
净利润率 = (净利润 ÷ 销售收入) × 100%
Return on Capital Employed (ROCE) = (Net Profit ÷ Capital Employed) × 100%, where capital employed = total assets − current liabilities, or non-current liabilities + capital.
资本报酬率 (ROCE) = (净利润 ÷ 运用资本) × 100%，其中运用资本 = 总资产 − 流动负债，或非流动负债 + 资本。
Liquidity ratios assess short-term survival:
流动性比率评估短期偿债能力：
Current Ratio = Current Assets ÷ Current Liabilities. A ratio of ~2:1 is typically considered healthy, but depends on industry.
流动比率 = 流动资产 ÷ 流动负债。通常 2:1 左右被视为健康，但依行业而定。
Acid Test (Quick) Ratio = (Current Assets − Inventory) ÷ Current Liabilities. This measures immediate liquidity, with ~1:1 often desirable.
速动比率 = (流动资产 − 存货) ÷ 流动负债。衡量即时流动性，通常 ~1:1 较为理想。
Trade receivables collection period (in days) = (Trade Receivables ÷ Credit Sales) × 365, or (Trade Receivables ÷ Sales) × 365 if credit sales not given.
应收账款周转天数 = (应收账款 ÷ 赊销净额) × 365，若赊销额未知可用销售收入。
Trade payables payment period = (Trade Payables ÷ Credit Purchases) × 365.
应付账款付款天数 = (应付账款 ÷ 赊购净额) × 365。
Rate of inventory turnover (times) = Cost of Sales ÷ Average Inventory, or in days: (Average Inventory ÷ Cost of Sales) × 365.
存货周转率（次）= 销货成本 ÷ 平均存货，或天数：(平均存货 ÷ 销货成本) × 365。
9. Marginal Costing & Break-even | 边际成本与盈亏平衡
Marginal costing separates costs by behaviour: variable costs change with output; fixed costs remain constant within a relevant range. Contribution is the difference between sales revenue and total variable costs.
边际成本法按性态划分成本：变动成本随产量变化；固定成本在相关范围内保持不变。贡献毛利是销售收入与总变动成本之差。
Contribution per unit = Selling price per unit − Variable cost per unit
单位贡献毛利 = 单位售价 − 单位变动成本
Total Contribution = Contribution per unit × Number of units sold
总贡献毛利 = 单位贡献毛利 × 销售数量
Break-even point (in units) = Total fixed costs ÷ Contribution per unit
盈亏平衡点（单位）= 总固定成本 ÷ 单位贡献毛利
Break-even point (in sales value) = Total fixed costs ÷ Contribution to Sales (C/S) ratio, where C/S ratio = (Contribution per unit ÷ Selling price per unit) × 100%.
盈亏平衡点（销售额）= 总固定成本 ÷ 贡献毛利率(C/S)，其中 C/S 比率 = (单位贡献毛利 ÷ 单位售价) × 100%。
Margin of safety = Actual or budgeted sales units − Break-even sales units. It can also be expressed as a percentage of budgeted sales.
安全边际 = 实际或预算销售量 − 盈亏平衡销售量。也可表示为预算销售的百分比。
Target profit analysis: Required units to achieve target profit = (Total fixed costs + Target profit) ÷ Contribution per unit.
目标利润分析：达成目标利润所需销量 = (总固定成本 + 目标利润) ÷ 单位贡献毛利。
Charts: a break-even chart plots total costs and total revenue; the intersection shows break-even. Limitations include assumption of constant selling price and variable cost per unit, and that all output is sold.
图表：盈亏平衡图绘制总成本与总收入线；交点表示盈亏平衡。其局限包括假设售价和单位变动成本不变，以及所有产品全部售出。
10. Budgeting & Variance Analysis | 预算与差异分析
A budget is a quantitative financial plan for a future period. For WJEC, the focus is often on cash budgets and simple operating budgets.
预算是未来期间的定量财务计划。WJEC 通常侧重于现金预算和简单经营预算。
A cash budget forecasts receipts and payments, highlighting net cash flow and closing bank balance. Key items: cash sales, receipts from credit customers, payments for purchases, wages, overheads, and capital expenditure.
现金预算预测收入与支出，突出净现金流量和期末银行存款余额。关键项目：现金销售、赊销客户回款、购货付款、工资、间接费用及资本支出。
Variance analysis compares actual results with budgeted figures. For sales and costs, a variance is calculated as: Variance = Actual − Budget. A favourable variance arises when actual profit is higher than budget (or cost lower); adverse (unfavourable) when actual profit is lower (or cost higher).
差异分析对比实际结果与预算数字。对销售和成本而言，差异计算公式为：差异 = 实际数 − 预算数。当实际利润高于预算（或成本较低）时产生有利差异；反之为不利差异。
Sales volume variance: measures the impact of selling a different volume than planned. Sales price variance: isolates the effect of selling at a different price.
销售量差异：衡量实际销量与计划不同的影响。销售价格差异：单独衡量售价变化的影响。
For direct materials: price variance = (Standard price − Actual price) × Actual quantity purchased; usage variance = (Standard quantity for actual output − Actual quantity used) × Standard price.
直接材料：价格差异 = (标准价格 − 实际价格) × 实际采购量；用量差异 = (实际产量下的标准用量 − 实际用量) × 标准价格。
For direct labour: rate variance = (Standard rate − Actual rate) × Actual hours; efficiency variance = (Standard hours for actual output − Actual hours) × Standard rate.
直接人工：工资率差异 = (标准工资率 − 实际工资率) × 实际工时；效率差异 = (实际产量下的标准工时 − 实际工时) × 标准工资率。
Variances should be investigated if material. They help management take corrective action and improve future planning.
差异若重大应予以调查。它们帮助管理层采取纠正措施并改进未来计划。
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