Cost plus pricing is a method of setting a selling price by taking a measured cost for the thing being sold and adding a markup to it. It is a pricing method rather than a contract type, and the two get confused constantly: a cost plus contract is an agreement about how a buyer reimburses a seller, worked through in cost plus contract, while cost plus pricing is a decision a seller can make with no contract of that kind anywhere in sight.
price = cost base x (1 + markup)Both inputs are choices, and neither is given by the accounting records on its own.
Which Cost Goes in the Base
A business can build the base from variable cost alone, from full absorbed cost including a share of fixed overhead, or from something in between. The choice moves the markup that gets to the same price, not the price itself.
variable cost per unit 60
allocated fixed cost per unit 25
--
full cost per unit 85
to reach a price of 110:
markup on full cost (110 - 85) / 85 = 29.4%
markup on variable cost (110 - 60) / 60 = 83.3%Two markups, one price, one product. This is why a markup percentage quoted without its base is uninterpretable, and why comparing your markup with a competitor’s is meaningless until you know what each is a markup on. The traceability question behind which costs can be pushed into the base at all is set out in direct cost, and the machinery that spreads the fixed portion is in costing overheads.
Full cost is the more common base because it makes every unit look like it is covering its share of everything. Variable cost is the honest base for an incremental decision, since fixed costs do not change when one more unit is sold.
Markup and Margin Are Not the Same Number
This is the single most common arithmetic error in the method, and it is expensive because it runs on every transaction.
A markup is stated on cost. A margin is stated on price. The same money produces two different percentages.
cost 100, markup 40%
price = 100 x 1.40 = 140
margin = 40 / 140 = 28.6%
to earn a margin of 40% on that cost
price = 100 / (1 - 0.40) = 166.67
markup = 66.67 / 100 = 66.7%
markup = margin / (1 - margin)
margin = markup / (1 + markup)A business that wanted a 40% margin and applied a 40% markup is earning a margin more than a quarter below the one it aimed at, on every job, until somebody notices.
Where the Method Breaks
The circularity is the structural problem. Unit cost depends on volume, because fixed costs are spread over the units made. Price depends on unit cost. Volume depends on price. So a fall in volume raises unit cost, which raises the cost plus price, which lowers volume further. The loop is self-reinforcing and it runs in the direction nobody wants.
The second problem is that the method never looks at the buyer. A price set from cost is the same price whether the customer values the work at twice that or half of it, so a business using it exclusively leaves money on the table where it is strong and loses work where it is not. Cost sets a floor below which a sale destroys value. It does not identify a ceiling.
Neither is an argument for abandoning it. It is an argument for treating the output as a starting price to be tested against what the work is worth to the buyer, rather than as an answer.
Where Cost Plus Is Required Rather Than Chosen
Two settings take the decision out of the seller’s hands.
The first is regulated or reimbursed work, where a buyer agrees to pay allowable cost plus a fee and the rules govern what counts. That is contract territory and it lives in cost plus contract.
The second reaches a firm’s tax work. In transfer pricing between related parties, the cost plus method is a named method for testing whether an intercompany charge is arm’s length: it evaluates whether the amount charged in a controlled transaction is arm’s length by reference to the gross profit markup realized in comparable uncontrolled transactions, and it is ordinarily used in cases involving the manufacture, assembly or other production of goods sold to related parties (26 CFR 1.482-3(d)).
Note what that regulation does with the markup. It does not let the taxpayer pick one. The markup has to be drawn from comparable uncontrolled transactions, which turns cost plus from a pricing preference into an evidence problem.
Common Questions
Decide the cost base and say what it includes, then apply a markup to it. Check the result against the margin it actually produces before committing, because the markup and the margin are different percentages and the gap widens as the markup rises.
As a pricing method, yes, for ordinary commercial work. What is restricted is a particular contracting structure in federal procurement, where a system that pays a fee as a percentage of incurred cost is prohibited, a point covered in cost plus contract. The distinction is between how a seller decides its own price and how a buyer agrees to reimburse it.
Where a market price already exists, since customers will pay what the work is worth to them rather than what it cost to produce. Also where the cost base is dominated by allocated fixed overhead and volumes are falling, because that is exactly the setup the circularity punishes.
Accountably places trained offshore accountants and tax preparers inside US CPA and EA firms, and a firm can put a real block of its own recurring work through a trial task before anything client facing depends on it.
