Accounting Paper 1 Topic 22: Marginal Costing & Limiting Factors

A limiting factor (or key factor) is any scarce resource that restricts the volume of business output or sales in the short term. Common limiting factors include shortages of direct raw materials, skilled labour hours, machine operating hours, or sales demand. In marginal costing, businesses prioritize products that yield the highest contribution per unit of that scarce resource.

Cambridge A Level Accounting Paper 1 frequently tests students on single limiting factor scenarios. Questions require candidates to calculate contribution per key factor, determine product rankings, and draft the optimal production schedule. Demonstrating speed and precision in these multi-step calculations is essential for scoring full marks on management accounting questions.

To decide product priority, calculate each product's contribution per unit, then divide it by the amount of the limiting factor required to make one unit. Rank products in descending order based on this contribution per unit of limiting factor. Always allocate scarce resources to meet full demand for the highest-ranking product before moving to the next.

Ranking by unit contribution ignores the rate at which different products consume the scarce resource. A product with a higher unit contribution might use significantly more machine hours or direct labour, yielding a lower contribution per hour than an alternative product. Maximizing total profit requires maximizing contribution per unit of the restricted resource.

Limiting factors is considered a moderately challenging topic because it requires sequential multi-step calculations within strict exam time limits. Errors in the initial contribution or resource requirement per unit cascade into incorrect rankings and production quantities. Topical past paper practice helps students master the workflow systematically.

Common errors include ranking products by selling price, unit contribution, or net profit instead of contribution per unit of limiting factor; miscalculating resource requirements per unit (e.g. confusing minutes with hours); failing to subtract total fixed costs when calculating final profit; and misallocating remaining scarce resources.

When production capacity is limited, a firm can purchase shortfall units from external suppliers to meet demand. The decision focuses on the extra cost of buying per unit of limiting factor saved: (Purchase Price - Variable Cost) / Limiting Factor per Unit. Products with the lowest extra cost per scarce resource saved should be bought externally first.

Begin by writing down the standard 5-step limiting factor procedure: calculate unit contribution, identify resource usage per unit, calculate contribution per limiting factor, rank products, and construct the production schedule. Solve all topical MCQs systematically and review the mark schemes to confirm calculation steps.

Typically, 1 to 3 multiple-choice questions appear on marginal costing decisions and limiting factors in every Cambridge Paper 1 examination. Because every MCQ contributes equally to the final grade, mastering this reliable calculation topic provides dependable marks.

Yes. This free downloadable PDF compiles authentic Cambridge past paper questions on Marginal Costing & Limiting Factors spanning 1999 to 2024. Organized chronologically with complete answer keys, it enables students to practice independently, assess their speed, and master limiting factor calculations before the exam.