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Marginal cost accounting (MCA) – How to make quick and accurate decisions

Marginal costing shows you in a flash whether an order covers variable costs—and thus brings in money in the short term.

Imagine this: a last-minute additional order lands on your desk. It could generate revenue – or it could eat into your margin without you noticing. Full cost accounting might say, “No, this order isn’t worth it.” But if you rely solely on this metric, you run the risk of missing out on profitable opportunities.

This is the strength of marginal costing. It shows you in no time at all whether an order covers the variable costs and thus immediately increases liquidity and contribution margin.

What makes marginal cost accounting different?

“Marginal costing is a method of cost accounting that only takes variable costs into account in order to enable quick and precise operational decisions.”

While full costing treats fixed and variable costs equally, marginal costing focuses exclusively on variable costs—i.e., those costs that fluctuate directly with the production volume, such as materials or manufacturing wages. Fixed costs such as rent, salaries, or depreciation are excluded because they cannot be changed in the short term and are irrelevant for short-term decisions.

The idea behind this is simple:
If an order covers its variable costs, every additional dollar contributes to covering the fixed costs, thereby reducing the fixed cost burden per unit.

When is MCA particularly useful?

Limit cost accounting supports you in situations where you have to make short-term decisions and only the costs incurred in the short term count. Typical areas of application are:

  • Special orders with discounts – you check whether the sales price at least covers the variable costs.
  • Bottleneck decisions – You identify which product generates the highest contribution margin per hour.
  • Assortment decisions – You identify which products contribute most to covering fixed costs and where adjustments are advisable.
  • Liquidity management – You can see at a glance which orders will bring in money in the short term.

Practical example: A quick check of an additional order

A manufacturing company receives an order for 1,000 units of a product—but at half the list price.

Full cost accounting rejects the order because the full fixed costs are not covered.

Marginal cost accounting comes to a different conclusion: the variable costs are covered and there is spare capacity available. Every additional euro above and beyond the variable costs contributes to covering the fixed costs. The company accepts the order and makes optimum use of its capacity, with a positive effect on liquidity.

What are the advantages of marginal cost accounting?

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What are the limitations of MCA? How can you overcome them?

Limit cost accounting reaches its limits

  • when the distinction between fixed and variable costs is unclear,
  • the assumption of linear cost curves does not apply,
  • or long-term effects play a role.

In these cases, it makes sense to combine MCA with an investment calculation.

MCA and investment appraisal: a strong team

The combination of marginal cost accounting (MCA) and investment appraisal is particularly worthwhile for medium-sized companies.

MCA provides precise data on variable unit costs and contribution margins.

Investment appraisal complements this view by taking into account fixed costs, long-term cash flows, profitability, and amortization.

An example:

You are planning to purchase a new production line. Using MCA, you determine that the variable unit costs would fall from 50 euros to 45 euros—a saving of ten percent per unit.

Conclusion: Clarity for quick decisions

You then use investment appraisal to check whether this investment will pay off over five years. To do this, you run through various sales and interest rate scenarios. The result is a clear, reliable investment decision that takes into account both the short-term cost advantages and long-term profitability.

If you want to make quick and informed decisions, you will benefit from marginal cost accounting (MCA). It provides a clear basis for decision-making where full cost accounting only provides average values.

Our advice:

Apply MCA to your next special order and compare the result with your previous calculation. You will quickly see how much clarity this method creates—and how it improves the quality of your decisions.

Digression: Marginal cost accounting in Business Central

However, these standard tools have their limitations when it comes to the practical application of MCA: there are only two dimensions (cost center and cost object), no multi-level contribution margin accounting, no MCA-specific planning procedures, and no preconfigured analysis templates. In addition, a high level of post-processing in Excel is often required. An addition is useful and helpful here.

Microsoft Dynamics 365 Business Central already has integrated cost accounting with important basic functions: cost types, cost centers, cost objects, budget and actual recording, allocations, cyclical distributions, and a step procedure for separating fixed and variable costs – a solid basis for marginal cost accounting (MCA). Standard reports for cost center and cost object analyses are also included.

Marginal cost accounting with CKL

CKL offers specialized add-ons that close these gaps – from multidimensional contribution margin accounting and automated separation of fixed and variable costs to complete planning and actual procedures based on the German GPK model. The solutions integrate seamlessly into Business Central and are even Copilot-enabled.

Practical insight:

In the free CKL webinars, you can see live how the two systems interact and ask your questions directly. An ideal introduction to getting to know the MCA functions in combination with Business Central.

Click here for the next dates and to register: Webinars.

FAQ on marginal costing (MCA)

What is the difference between marginal costing and full costing?
Marginal costing (MCA) only takes variable costs into account. Fixed costs are not considered because they cannot be changed in the short term and are therefore irrelevant for short-term decisions.

Is MCA implemented in Business Central?
Partially. Microsoft Dynamics 365 Business Central provides basic functions for cost accounting. However, extensions such as the CKL add-ons are required for complete, automated contribution margin accounting or a clear separation of fixed and variable costs.

For what size of company is MCA worthwhile?
MCA makes sense wherever decisions have to be made about orders, products, or bottlenecks—in other words, in almost every medium-sized company with its own production or a high level of service depth.

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