--- title: "Payment fees varied by tender and went unmanaged | MarginFix" description: "Interchange and scheme fees differed sharply by payment type with no steering or review. Marketing & margin audit: $38k/yr in margin identified." url: https://marginfix.ai/cases/payment-fees-varied-by-tender-and-went-unmanaged/ lastmod: 2026-10-28 --- Payment fees varied by tender and went unmanaged. [Request an audit →](/book/) Retail · Convenience # Payment fees varied by tender and went unmanaged. This marketing & margin audit surfaced **$38k in annual margin** in a Retail business, evidenced, senior reviewed, and delivered in 5 days. $1–3M annual revenue Convenience Focus: Payment fees +$38k margin recovered / yr +2pts tender margin 5 days to findings Blended card processing rate Before audit 1.9% → After fix 1.5% ## The business A convenience store operator accepted a wide range of payment types across its estate, from cards and mobile wallets to scheme specific and premium cards. Payment fees were treated as a fixed, unavoidable cost of doing business, so the sharp differences in interchange and scheme fees between tender types were never analyzed or actively managed. ## What triggered the audit Payment fees as a share of revenue were higher than the tender mix seemed to justify, hinting the costlier tenders were overrepresented. The audit broke payment cost down by tender type across the estate, testing where fees were quietly eating margin and whether anything could steer the mix. ## What the audit found Payment cost varied far more by tender than anyone had managed for. Certain premium cards and scheme types carried materially higher interchange and processing fees than standard debit or account to account options, and on the thin margins typical of convenience retail, that difference was significant on every transaction. Because fees were treated as a fixed cost and never analyzed by tender, the estate was absorbing the most expensive payment types without any steering, surcharging where permitted, or negotiation, and the costliest tenders were overrepresented in the mix. The leak was invisible precisely because “payment fees” was accepted as an immovable line. Broken down and managed, the unmanaged tender fee differential was costing roughly $38k a year in avoidable processing cost. ◉ How we produced this finding Behind the payment fees finding is a from scratch margin rebuild: MarginFix recalculated retail profitability per unit and per order using real costs, not assumptions, then had a named senior auditor confirm the contribution margin read against the client’s own data before it was released. Data sources: Cost of goods, payment fees inputs, fulfillment, fees, returns and discounts, reconciled per unit and per order, so the true contribution margin behind every single sale is visible rather than assumed. Key frameworks: A full contribution margin and cost to serve rebuild, full cost ROAS and margin based ROI analysis, framed by the Enterprise Marketing ROI Framework that treats spend as a capital allocation decision. Human validation gate: Every number is rebuilt on your own cost data and signed off by a named senior auditor before it ships. No figure leaves the building without a human standing behind it. Verified against POS / invoice ledger Fee & surcharge schedules Landed cost sheet Promo calendar Finance P&L The margin recovered / yr was measured like for like over a matched period, reconciled to invoiced margin in the P&L, and signed off by a named senior auditor before publication. Client identity redacted to protect their commercial position. WORKING PAPER ████████ Convenience Representative Redacted Payment type Processing rate Contactless 1.4% Chip & PIN 1.6% Manual / online 1.9% margin recovered / yr +$37,780 Recurring, recovered every year the fix holds, not a one off. Working paper: blended card processing rate traced line by line and reconciled to invoiced margin in the P&L over a matched period. Line items representative and redacted; the recovered figure is the reconciled audit finding. ## What we changed ✓ Broke payment cost down by tender type across the whole estate, making the interchange and scheme fee differential visible and manageable for the first time. ✓ Steered customers toward lower cost tenders where permitted, through prompts, minimum spend rules and account to account payment options. ✓ Renegotiated processing and scheme terms using the detailed tender mix data as concrete leverage with providers. ✓ Made payment cost by tender a monitored metric, so a gradual drift toward the most expensive tenders is caught and corrected before it quietly erodes already thin retail margin. ## The result The published chart shows the blended card processing rate falling from 1.9% to 1.5%, a 0.4 percentage point decrease. The separately reported 2 point tender margin improvement is a different measure and is not presented as that rate movement. $38k a year recovered by managing payment fees that everyone had written off as fixed, an annual figure equal to 6× the $5,950 Audit + Sprint fee. For any high volume, thin margin retailer, that’s the trap: “payment fees” is accepted as immovable, so a costly tender mix erodes margin on every transaction unmanaged. If you’ve never broken fees down by tender, expensive payment types may be overrepresented and quietly taxing you. A fixed fee audit breaks it down in days and turns a “fixed” cost into a managed one. From kickoff to signed off findings: 5 days. ![Portrait photograph of David Jackson](/assets/team/david-jackson.jpg) Reviewed & signed off by: David Jackson Senior Auditor · MarginFix · 10+ years of auditing experience ✓ Anonymized to protect the client · senior reviewed findings · Audit completed between 2024 and 2026, contracted through Cristian Bragau's practice before the MarginFix name existed · Published in the MarginFix library July 21, 2026 · Last reviewed October 28, 2026 [Request an audit →](/book/) [Prefer to talk it through first? Talk to an auditor →](/book/call/) ## More Retail findings [Free assembly and delivery were bundled below cost on big ticket lines, +$58k/yr](/cases/free-assembly-and-delivery-were-bundled-below-cost-on-big-ti/) [Online ads were paying for in store demand, −$88k/yr](/cases/online-ads-were-paying-for-in-store-demand/) [Loyalty points cost more than the repeat they drove, −$71k/yr](/cases/loyalty-points-cost-more-than-the-repeat-they-drove/) [Markdown timing was leaving margin on the shelf, +$49k/yr](/cases/markdown-timing-was-leaving-margin-on-the-shelf/) [Returns processing cost was missing from channel economics, $69k/yr](/cases/returns-processing-cost-was-missing-from-channel-economics/) [Click and collect was subsidizing the delivery it replaced, +$54k/yr](/cases/click-and-collect-was-subsidising-the-delivery-it-replaced/) [The benchmark: what audits recover across 74 cases →](/benchmark/) [All case studies](/case-studies/) [Model a Retail budget in the wasted ad spend calculator →](/estimator/retail/)