A recurring membership charge is not a margin. Members can generate revenue on one timetable and use wash capacity on another. Connect the billing population, earned revenue, visits and cost behavior before interpreting a growing membership base as stronger earnings.
Keep members, money and visits separate
Choose a complete month, site scope and consistent member unit: account, subscription, household or vehicle. Distinguish average billable member-equivalents from a month-end active count. The optional average supports a per-member contribution measure; it does not replace the opening-to-closing population bridge.
Reconcile earned revenue to charges, discounts, refunds, prepaid service and remaining obligations. Use the cohort tool for member movements and opening-cohort retention, and the worked revenue case for POS, processor and bank timing. A successful bank collection is not automatically the month's earned revenue.
One public operator's filing describes its subscription recognition policy; it is a named example rather than a margin or retention benchmark. Mister Car Wash · SEC filing: 2025 Form 10-K. Have the accountant determine the actual treatment. NY sales-tax guidance distinguishes services and payment arrangements; enter revenue excluding tax collections instead of applying one assumed tax rule to every wash. NYS Department of Taxation and Finance: Car wash services · TB-ST-105.
Define the costs that move with service or billing
Separate a cost per visit from a cost per billing event and a cost that recurs over time. A processor fee on a monthly subscription charge should not be deducted again for every wash visit. A minimum utility charge, scheduled shift or fixed software payment does not necessarily decline when wash count falls.
| Input | Evidence and caution |
|---|---|
| Earned plan revenue | Matched period; net of tax, discounts and refunds under the declared basis. |
| Visits | Consistent count of completed member or retail services, not card charges. |
| Direct cost per visit | Measured or supported consumption and variable costs; avoid duplicated period costs. |
| Billing and processing fees | Actual plan/retail period fees and source definition. |
| Other direct variable costs | Costs not already in the per-visit or billing fields. |
| Selected fixed site costs | Explicit list of included costs and omissions. |
| Higher-case staffing step | Additional fixed cost that the higher service level would require. |
SBA's contribution framework distinguishes fixed, variable and mixed costs. US Small Business Administration: Break-even and fixed/variable cost framework. The plan/retail model here is an original extension with explicit definitions. Do not populate it with a chain operator's margin or a generic chemical range.
Use consumed chemicals rather than purchases alone
Reconcile opening stock plus purchases minus closing stock on a consistent valuation basis. Adjust documented transfers, returns, waste and count errors before interpreting consumption. In a fictional month, $2,500 opening inventory + $4,000 purchases − $2,000 closing inventory gives $4,500 consumed. Over 3,000 matched washes, that is $1.50 per wash.
That $1.50 is a teaching calculation, not a dosing instruction or industry norm. Package mix, equipment, chemistry, dilution, reclaim and service type matter. The chemical-cost guide shows the evidence bridge. Utility usage and billed periods need the separate meter and bill reconciliation.
Work the member-versus-retail contribution case
The example has 500 average members, $15,000 earned membership revenue and 2,000 member visits, with $450 billing fees. Retail has $14,000 earned revenue, 1,000 visits and $420 processing fees. Both use an invented $2.50 direct variable cost per visit and zero other direct variable period costs.
Member contribution = 15,000 − 2,000 × 2.50 − 450 = 9,550 Retail contribution = 14,000 − 1,000 × 2.50 − 420 = 11,080 Combined contribution = 20,630 Selected-cost surplus = 20,630 − 18,000 selected fixed costs = 2,630
Increase only member visits to 3,500. Member contribution becomes $5,800, and the selected-cost result becomes −$1,120 before any additional staffing step. Revenue and period billing costs are held fixed deliberately. This shows service burden; it does not predict visits, cancellations, pricing response or net profit.
Read break-even and sensitivities within their limits
The retail break-even threshold divides fixed costs remaining after member contribution by observed retail contribution per visit. It holds the entered retail mix, ticket and cost behavior fixed. A zero visit count yields no observed unit margin, and nonpositive retail contribution yields no finite threshold. Fractional visits are an algebraic threshold, not an operating plan.
Enter zero only for a documented cost that does not apply. Leave an entire unused membership row blank; any used row needs complete required economics. Negative net revenue remains visible for refunds. Zero average members makes a per-member ratio undefined, while the dollar contribution still calculates.
The higher-usage case includes a separately entered staffing step. Review actual shift coverage in the owner replacement planner and service constraints in the throughput case. More modeled visits do not establish attainable capacity or permission to change site use.
Connect contribution to the acquisition decision
List omitted depreciation, financing, income taxes, capital projects and any other costs before interpreting surplus. Do not apply a membership valuation premium or automatic lifetime value. Reconcile a supported annual operating case to monthly reported earnings before using the annual acquisition calculator.
Confirm whether billing rights, software access and customer obligations can continue under the actual transaction structure. Do not copy payment details or assume provider access transfers. The closing handoff assigns the responsible roles and effective times.
Download the blank evidence worksheet
Download the fictional teaching case v1
Refresh the case when behavior or costs change
The operator maintains visit and consumption evidence; the accountant reconciles earned revenue and costs. Revisit package changes, pricing, promotions, vendor terms and staffing steps. The editor reviews the framework annually and revisits tax sources when revised. No recommended price, churn forecast or investment return is supplied.
Questions before using the result
Does higher membership revenue prove higher profit?
No. Review the cost of serving visits, billing charges, fixed costs and omitted expenses, as well as revenue quality and retention.
Can I divide monthly membership cash by visits as the selling price of each wash?
That ratio may describe a selected period, but it does not establish per-visit earned revenue or change the subscription obligation.
Why is retail break-even undefined?
The observed retail visit count is zero, or contribution per retail visit is nonpositive. The tool does not invent a positive margin or demand forecast.
Connect the next evidence question
Membership billing continuity. Each workbook has its own scope, written method and fictional case. Reconcile definitions before manually carrying a result into another review.
Connect operating evidence and the next decision
Retail package pricing and mix · Chemical inventory and usage. Keep periods and definitions consistent when manually carrying results between tools.
Sources and scope
Official and original sources checked October 17, 2026. These sources support the identified rules and methods; they do not verify a particular business or property.
- Mister Car Wash · SEC filing — 2025 Form 10-KOne public operator's membership revenue recognition and POS-to-bank audit; not a small-business margin benchmark.
- US Small Business Administration — Break-even and fixed/variable cost frameworkContribution arithmetic and fixed, variable and mixed cost definitions. No car wash benchmark or default cost assumptions are adopted.
- NYS Department of Taxation and Finance — Car wash services · TB-ST-105Service, assistance and payment method affect sales-tax treatment.
Continue your review
Verify the revenue · Normalize earnings · Model the cash flow