The short version
- Flat rate is simple, but payments with very different underlying costs can carry the same markup.
- Complete interchange-plus statements separate network and issuing-bank costs from processor markup, helping you compare offers.
- Dual pricing can lower the shop's merchant percentage for credit and debit. The shop must also manage price displays, customer explanations and payment workflow.
No pricing model is always best. A 2.9% flat rate, interchange plus 30 basis points and a 0% merchant card rate carry different costs and responsibilities for the shop.
Apply each proposal to the same three months of transactions. Keep volume, card mix and included fees consistent across the comparison, even if a salesperson uses different assumptions in their presentation.
Browse the complete auto repair guides and worksheets.
Check your own costs: calculate your effective processing rate or upload a merchant statement for analysis.
What each pricing model includes
| Model | Basic structure | Owner tradeoff |
|---|---|---|
| Flat rate | A single advertised percentage, often with a transaction charge | Easier to forecast, with less detail about the underlying card cost |
| Interchange plus | Network and issuing-bank costs with a separately stated processor markup | More visible cost components, though card mix still changes the monthly bill |
| Dual pricing | A regular card price and lower cash price for eligible, configured credit and debit payments | The merchant percentage may be lower; disclosure and customer workflow need more attention |
Flat rate: weigh simplicity against the price
A flat rate makes the basic charge easy to explain and estimate: the posted percentage plus a transaction charge. A small mobile mechanic or low-volume part of the business may value that simplicity more than a small rate reduction.
The same percentage can apply to cards with different underlying costs. A regulated debit payment may cost the provider much less than a premium rewards payment, while the shop pays the same rate. Keyed, international, chargeback, hardware and software costs may still be separate.
Interchange plus: see the underlying cost and markup
Interchange plus lists the underlying card cost separately from processor markup. When the statement shows those components clearly, you can distinguish the effect of your card mix from the provider's added charge.
Ask exactly what the plus includes: percentage markup, cents per transaction, monthly charges and event fees. A cost-plus offer needs to state that markup in writing.
- Get both the percentage markup and the per-transaction markup.
- Ask whether network assessments are passed through without markup.
- Include monthly minimums, PCI, gateway, batch, equipment and annual fees in your list.
- Calculate the offer using your actual card categories and payment channels.
Dual pricing: consider the customer experience too
Properly configured dual pricing can give eligible credit and debit transactions a 0% merchant processing rate, with the payment cost reflected in the regular card price. Monthly, chargeback, gateway and other account charges may still apply.
The shop also takes on the work of displaying prices clearly, training advisors, testing debit and payment links, matching repair-order totals and responding to customers. Assign responsibility for that work so the lower rate doesn't produce confusion at pickup.
Compare proposals on the same basis
- Gather three months of transactions, separated by card type and payment channel.
- Calculate each proposal's percentage, transaction, monthly, equipment, gateway and event charges.
- Allow for realistic changes in cash, debit, credit, ACH, checks and financing.
- Include the cost of integration, reconciliation, staff training and contract commitments.
- Review funding, support, chargeback tools, refunds, who owns the equipment and how cancellation works.
- For each full scenario, calculate both total cost and effective rate.
Where each model may fit
Flat rate may suit a mobile mechanic taking only a few card payments. Interchange plus may offer more to a larger shop with consistent systems and an owner who reviews statements. Dual pricing may fit an independent shop with large tickets, high card volume and well-prepared advisors.
Treat those examples as starting points, not fixed rules. The right model depends on the shop's actual transactions, staff and payment process.
Questions business owners ask
Will interchange plus cost less than flat rate?
Not necessarily. It usually shows the costs more clearly, but card mix, markup, payment count, fixed fees and channels determine the final bill.
Will dual pricing always give the shop the lowest cost?
No. Remaining fees, card mix, changes in how customers pay, integration work and effects on customers all influence the result.
How do I compare offers with different fee structures?
Use the same transaction data for each offer, include every recurring and event charge, then compare total cost and effective rate.
Primary sources
BlueFinch last reviewed these sources on August 11, 2026. Payment rules and state requirements can change.
- Visa: Credit Card Processing Fees and Interchange Rates
- Chase Payment Solutions: Understanding Your Processing Statement
Use this page for general business information. It is not legal, tax, or accounting advice.