Sales commission paid as a percentage of revenue is a variable cost. Whether sales commission is a fixed or variable cost comes down to how it’s structured: total commission expense rises and falls in lockstep with sales volume, which is the defining trait of variable cost behavior. When a company also pays a guaranteed base salary or a non-recoverable draw, that guaranteed portion is fixed, and the overall compensation package becomes a mixed cost.
Fixed and Variable, Briefly
A fixed cost stays the same in total regardless of how much you sell. Office lease, annual insurance premiums, salaried executive pay. You owe the same amount whether revenue doubles or drops to zero. “Fixed” only holds within a realistic operating range; outgrow the warehouse and rent jumps to a new fixed level.
A variable cost moves in proportion to activity. Sell twice as many units and total variable cost roughly doubles. Raw materials, packaging, shipping. The total changes, but the cost per unit stays constant.
Why Pure Commission Is Variable
When a salesperson earns only a percentage of the revenue they generate, the math is clean. A 5% commission rate on $100,000 in sales produces exactly $5,000 in commission expense. If sales climb to $200,000, commission doubles to $10,000. If sales fall 20%, commission falls 20%. No floor, no lag. The expense exists only because a sale happened, and it scales at a constant rate per dollar of revenue.
That perfect proportionality is what makes pure percentage-based commission the textbook example of a variable selling cost. It ties to revenue rather than production volume, so it belongs in variable selling expenses, not in cost of goods sold.
When Commission Becomes a Mixed Cost
Most companies don’t pay pure commission. The more common structure combines a guaranteed base salary with a commission percentage on top. A rep earning $50,000 per year plus 10% on all sales has a compensation package with both fixed and variable elements.
The $50,000 base is fixed. You owe it regardless of performance. The 10% commission is variable. For any financial analysis worth doing, separate the two. Lumping them together as a single line item distorts contribution margin and throws off break-even calculations. The base salary goes into your fixed cost pool. The commission percentage goes into your variable cost per dollar of revenue.
Where companies get into trouble is treating the entire package as variable because “they’re in sales.” A rep earning $50,000 in base and generating $300,000 in revenue at 10% costs the company $80,000 total. Only $30,000 of that is variable. Treating the full $80,000 as variable understates fixed costs and makes the break-even point look lower than it is.
Non-Recoverable Draws Behave Like Salary
A draw is an advance paid against future commissions, common during onboarding or slow seasons. A non-recoverable draw guarantees a minimum payout each period regardless of performance. If the rep earns less than the guaranteed amount, the company covers the gap and never claws it back. If the rep earns more, they keep the full commission.
That guaranteed floor behaves like a fixed cost. Anything earned above it is variable. Non-recoverable draws catch people off guard in cost models because they look like commission on the surface, but the guaranteed portion needs to sit alongside base salaries in the fixed cost pool. A recoverable draw, by contrast, is just a timing mechanism: the salesperson pays it back out of future commissions, so it ultimately resolves into ordinary variable commission expense.
Tiered Rates Are Still Variable
Many companies use graduated rates where the commission percentage steps up after a rep hits certain thresholds. 5% on the first $100,000, 8% on the next $100,000, 12% above $200,000. The total commission expense still rises with sales volume, so it remains a variable cost. But the rate per dollar isn’t constant across all output levels.
For rough budgeting, treating tiered commission as a simple variable cost works fine. For precise contribution margin analysis, model each tier separately or use a blended effective rate based on your expected sales mix. The blended approach works when sales volume is predictable. If volume swings dramatically between tiers, the blended rate loses accuracy and you’re better off treating each tier as its own variable cost layer.
Why the Classification Changes Your Break-Even Math
The reason any of this matters comes down to two calculations that drive pricing and profitability decisions: contribution margin and break-even point.
Contribution margin is revenue minus all variable costs, including commission. Sell a product for $100, spend $40 on materials, $10 on shipping, and pay a 10% ($10) commission, and contribution margin per unit is $40. The contribution margin ratio is 40%. Every dollar of revenue contributes $0.40 toward covering fixed costs and generating profit.
Break-even point in dollars equals total fixed costs divided by the contribution margin ratio. If fixed costs are $200,000 and the contribution margin ratio is 40%, you break even at $500,000 in revenue. Misclassify commission as fixed and the contribution margin ratio jumps to 50%, which makes the break-even point look like $400,000. That’s a $100,000 gap between what the model predicts and what reality requires.
The mistake isn’t exotic. Someone builds a model, drops the entire sales team cost into overhead as a fixed line, and the business suddenly looks profitable at a sales level that would actually lose money.
A Reporting Wrinkle That Doesn’t Change the Behavior
For managerial accounting and internal decision-making, commission is a variable selling expense. U.S. GAAP adds a separate layer for financial reporting.
Under ASC 340-40, companies must capitalize the incremental costs of obtaining a customer contract, and sales commissions are the most common example. An incremental cost is one you would not have incurred if you hadn’t won the deal. When a commission meets that test, it’s recorded as an asset on the balance sheet and amortized over the period you expect to benefit from the customer relationship, often the life of the contract including expected renewals.1PwC. Capitalization and Amortization of Incremental Costs of Obtaining a Contract
There’s a practical expedient: if the amortization period would be one year or less, you can expense the commission immediately rather than capitalizing it.2PwC. Costs to Obtain a Contract Most companies with standard annual contracts or month-to-month sales use this expedient. If your sales team closes multi-year deals, the commissions on those contracts likely need to be capitalized and amortized instead of expensed in full when paid.
None of this changes the underlying cost behavior. Commission is still variable for planning purposes. Capitalization only affects when the expense hits the income statement, which matters for reported earnings and cash flow timing, not for how you build a break-even model.