POS Processing Fees Explained: Flat-Rate vs Interchange-Plus vs Tiered

Almost every point-of-sale conversation eventually runs into the same wall: two processors quote what sounds like the same rate, the monthly bills come in hundreds of dollars apart, and nobody can explain why. Card processing pricing is deliberately hard to compare. This guide breaks down where the money actually goes, the four pricing models you will be quoted, the line items that quietly inflate your effective rate, how your own card mix and ticket size change the answer, and a method you can use to compare any two offers on a level playing field.

None of this requires an accounting background. If you can read a phone bill, you can read a merchant statement — you just need to know what the acronyms mean and which numbers are negotiable.

The three layers inside every card payment

When a customer taps a card for a $100 sale, the money that does not reach your bank account is split three ways. Understanding this split is the whole game, because only one of the three is something a salesperson can change.

• Interchange — paid to the bank that issued your customer’s card. It is set by Visa and Mastercard in published tables with hundreds of categories based on card type (debit, credit, rewards, corporate), how the card was accepted (tapped, dipped, keyed, online), your business category, and transaction size. Interchange is identical no matter which processor you use. Nobody negotiates it.
• Assessments / network fees — paid to Visa, Mastercard, Discover and Amex themselves. Small and fixed (roughly 0.13%–0.15% plus a few fixed fractions of a cent), and again the same across processors.
• Processor markup — what your processor, ISO, or POS company keeps. This is the only negotiable layer. On interchange-plus pricing it is stated explicitly. On flat-rate and tiered pricing it is blended into one number so you cannot see it.

Industry-wide, interchange plus assessments usually lands somewhere between 1.5% and 2.2% of volume for a typical card mix. So when someone quotes you a flat 2.6% + 10¢, a large part of that is pass-through cost and a smaller part — often 0.3% to 0.8% plus the fixed fee — is their margin. The entire skill of buying processing well is separating those two parts.

What interchange actually looks like

Interchange is not one number; it is a table with hundreds of rows. A few representative categories for a US card-present retailer give the shape of it:

• Regulated debit (large issuing bank): about 0.05% + 22¢. This is the cheapest common category by a wide margin.
• Unregulated / small-bank debit: often around 0.80% + 15¢.
• Basic consumer credit, card present: roughly 1.50%–1.80% + 10¢.
• Rewards consumer credit, card present: roughly 1.90%–2.10% + 10¢.
• Card-not-present or keyed consumer credit: roughly 2.30%–2.50% + 10¢ before any downgrade penalties.
• Commercial / corporate / purchasing cards: 2.50%–3.00%+, and these frequently require extra data to avoid a further downgrade.

Two things fall out of this table. First, the single biggest driver of your true cost is how much of your volume is regulated debit versus rewards and commercial credit. Second, how the card is accepted matters almost as much as which card it is — the same physical card costs more keyed than tapped.

Pricing model 1: Flat-rate (blended) pricing

Flat-rate pricing is what you get from Square, Shopify Payments, Stripe, PayPal and most all-in-one POS platforms. Every transaction is charged the same headline rate — a common example is 2.6% + 10¢ for a tapped or dipped card and 2.9% + 30¢ for an online or keyed one — regardless of what card the customer used or what the underlying interchange was.

Where flat-rate wins

• Predictability. You can forecast fees to the dollar, and your statement has one line, not forty.
• No monthly minimums, PCI fees, or statement fees in most cases — the headline rate is close to the whole story.
• Instant approval and no underwriting drama for small or new businesses.
• At low volume the absolute dollars are small, so the premium over interchange-plus is a rounding error.
• One vendor for software, hardware, and processing, which simplifies support.

Where flat-rate costs you

Because the rate is blended, you overpay on every transaction where the true interchange is low — most importantly regulated debit cards, where interchange is capped around 0.05% + 22¢. If a meaningful share of your sales are debit, a flat 2.6% is charging you roughly five times the pass-through cost on those transactions and keeping the difference.

A worked example. A business doing $40,000 a month in card sales, 45% of it on regulated debit, might pay about $1,040 a month on a 2.6% + 10¢ flat rate. The same volume on a well-priced interchange-plus deal (interchange + 0.25% + 10¢) often lands closer to $780–$850 once the cheap debit transactions are billed at their real cost. That is $2,000–$3,000 a year for identical sales.

Pricing model 2: Interchange-plus (cost-plus) pricing

Interchange-plus passes the interchange and assessment costs straight through to you and adds a fixed, disclosed markup — for example "interchange + 0.20% + 10¢". It is the model used by most established businesses and the one payment consultants recommend, because the processor’s margin is visible and constant.

How to read an interchange-plus quote

The two numbers that matter are the percentage markup and the per-transaction fee (the "plus" and the fixed cents). A competitive small-business markup is roughly 0.15%–0.35% plus 8¢–15¢. Anything above 0.50% + 15¢ for a healthy business is worth pushing back on. Ask for the markup in writing and confirm there is no separate "non-qualified surcharge" hiding on top — on true interchange-plus there should not be.

Why it is usually cheaper

• You pay the real (low) cost on debit and other low-interchange cards instead of a blended average.
• The markup does not scale with your ticket size the way a pure percentage does — a $400 sale and a $40 sale carry the same fixed markup cents.
• As card networks adjust interchange, your cost tracks it transparently rather than the processor pocketing the difference.
• Statements itemize every category, so you can actually audit what you paid.

The catch

Statements are longer and harder to read — you will see dozens of interchange categories itemized. There is often a monthly fee, a PCI compliance fee, and sometimes a monthly minimum. And underwriting is stricter, so brand-new businesses are sometimes steered to flat rate first. For most businesses past the startup phase, the transparency and lower effective cost are worth the busier statement.

Reading your first interchange-plus statement

The first cost-plus statement is intimidating. Work top-down: find the total volume and total fees, divide to get your effective rate, then look at the itemized section only to spot anomalies — a big block of "EIRF" or "standard" downgrades usually means keyed transactions or missing address data, and "non-qualified commercial" means business cards that need Level 2 data. Everything else is just categories doing what they should.

Pricing model 3: Tiered pricing (and why to avoid it)

Tiered pricing buckets every transaction into "qualified," "mid-qualified," and "non-qualified" tiers with rising rates — for example 1.7% qualified, 2.4% mid-qualified, 3.3% non-qualified. The pitch is a low headline "qualified" rate. The problem is that the processor decides which transactions qualify, and rewards cards, keyed transactions, and business cards routinely get downgraded to the expensive tiers.

In practice, tiered pricing makes your effective rate almost impossible to predict or audit, and the qualified rate you were sold often applies to a minority of your volume. If a quote mentions "qualified" and "non-qualified" rates, treat it as a red flag and ask for interchange-plus instead. There is no card mix for which tiered is the best available deal.

Pricing model 4: Membership / subscription pricing

A smaller group of processors charge interchange and assessments at cost, add little or no percentage markup, and instead charge a flat monthly membership fee (for example $99–$199/month) plus a small fixed per-transaction fee. For high-volume businesses with large average tickets this can be the cheapest model of all, because you are not paying a percentage markup on six-figure monthly volume. For low-volume businesses the fixed membership fee swamps the savings. It is worth modeling only once you are well into five figures a month.

How your card mix changes the answer

The "best" pricing model is not a fixed fact; it depends on your transactions. Three variables move the needle most:

• Debit share. The more regulated debit you take, the worse flat-rate looks, because flat-rate charges the same percentage on a card that truly costs almost nothing. A convenience store at 70% debit is leaving serious money on the table with a blended rate.
• Rewards and commercial credit share. B2B sellers and businesses in affluent areas see more premium and corporate cards, which carry high interchange. Flat-rate actually protects you a little here, but interchange-plus with proper Level 2/3 data still wins.
• Card-present vs card-not-present. Online, phone, and keyed transactions carry higher interchange and higher fraud exposure. If you are mostly e-commerce, compare card-not-present pricing specifically, not the in-person headline.

How average ticket size changes the math

Every pricing model has a fixed per-transaction fee (the "+ 10¢" part, plus batch and authorization fees). On a $4 coffee, a 10¢ fixed fee is 2.5% all by itself; on a $400 furniture sale it is 0.025%. Businesses with small average tickets should weight the fixed fees heavily and negotiate them down, and should be sceptical of any quote with a high fixed component. Businesses with large tickets can tolerate a slightly higher fixed fee in exchange for a lower percentage.

The fees hiding on your statement

The headline rate is only part of your effective cost. When comparing offers, get every one of these in writing, as a number, with the frequency it is charged:

• Monthly / account fee — a flat platform charge, commonly $0–$40.
• PCI compliance fee — $5–$20/month, sometimes with a separate annual fee and a "non-compliance" penalty if you skip the questionnaire.
• Statement fee — $5–$15/month for the privilege of receiving a bill.
• Monthly minimum — if your fees do not reach, say, $25, you are billed the difference.
• Batch fee — a few cents each time you settle the day’s transactions.
• Authorization fee — a few cents per authorization attempt, separate from the transaction fee, on some interchange-plus plans.
• Gateway fee — for online or virtual-terminal transactions, $5–$25/month plus a per-transaction charge.
• Chargeback fee — $15–$25 per dispute, win or lose.
• PayFac / platform fee — some POS companies add their own margin on top of the processor’s.
• Cross-border and currency fees — extra fractions of a percent on international cards.
• Early termination fee — $95–$500+ if you leave before the contract ends, sometimes calculated as "liquidated damages" on projected future revenue.
• Equipment lease — the most expensive line of all when present, because leases often run 48 months non-cancellable for hardware worth a few hundred dollars.

Debit routing, PIN debit, and least-cost routing

In the US, most debit cards can run over more than one network, and the networks price differently. "Least-cost routing" (sometimes "smart routing") automatically sends each debit transaction over the cheaper network. If you take a lot of debit, ask whether a processor supports it and whether it is on by default. PIN debit — where the customer enters a PIN rather than signing or just tapping — can also be cheaper per transaction for larger tickets, though the gap has narrowed and the customer experience is slower.

Negotiating your markup

On interchange-plus, the markup is the negotiable number, and processors expect you to push. A few tactics that work:

1. Bring a competing written quote. Nothing moves a markup like a rival offer on paper.
2. Ask for the markup as basis points, not a percentage, so small differences are visible — 25 bps versus 40 bps looks like nothing and costs real money.
3. Negotiate the fixed fees separately: monthly, PCI, statement, and batch. These are often pure margin and processors will waive them to close.
4. Refuse equipment leases outright. Buy hardware, finance it interest-free if offered, or use hardware you own.
5. Ask for a rate review in writing after 3–6 months once your real card mix is visible.

The single most useful number in payments is your effective rate on a real month of sales. Everything on a sales sheet is marketing until you divide total fees by total volume.

How to actually compare two quotes

Never compare headline rates. Compare effective rate — total fees divided by total card volume — on the same real month of your own sales. Here is the process:

1. Pull one representative month of card transactions from your current POS: total volume, transaction count, and if possible the split between debit, credit, and card-not-present.
2. Take your current statement for that month and add up every fee: processing, monthly, PCI, statement, batch, authorization, gateway, minimums, chargebacks. Divide the total by card volume. That is your current effective rate.
3. Send that same transaction profile to each processor you are considering and ask them to quote an all-in monthly cost for it, itemized.
4. For flat-rate offers, the math is simple: rate × volume + (fixed fee × count).
5. For interchange-plus offers, estimate interchange at roughly 1.7%–1.9% of volume for a card-present retail mix (higher for card-not-present or rewards-heavy), then add the disclosed markup and all monthly fees.
6. Compare the effective rates, not the headline rates. A "2.6%" and a "2.5%" can easily be 0.4 points apart once the junk fees are in.
7. Repeat with a second month if your business is seasonal — a December mix and a February mix can point at different winners.

When it is worth switching pricing models

Rough guidance, assuming a typical card-present business:

• Under ~$10,000/month in card volume: stay on flat rate. The simplicity is worth more than the small savings, and monthly fees on other models eat the difference.
• ~$15,000–$25,000/month: get interchange-plus quotes. This is where the blended premium starts to cost real money, especially if you take a lot of debit.
• ~$80,000/month and up, with larger tickets: model membership / subscription pricing as well. Not paying a percentage markup on that volume can be decisive.
• Any volume, if you are on tiered pricing: switch. Tiered is almost never the best deal and never the most transparent.
• Any volume, if you are on an equipment lease: get out at the earliest contractual opportunity and buy hardware instead.

High-risk, seasonal, and international considerations

If your business is classed as high-risk (travel, events, supplements, anything with high chargeback or future-delivery exposure), expect higher markups, rolling reserves, and stricter contracts — shop specialists rather than mass-market processors. If you are highly seasonal, watch for monthly minimums and account fees that bite in your off months, and negotiate them to zero. If a meaningful share of your customers use non-US cards, compare cross-border and currency-conversion fees explicitly, because they vary widely.

Questions to ask every processor before you sign

• Is this interchange-plus, flat, tiered, or membership pricing? What is the exact markup in basis points?
• List every recurring fee and its amount: monthly, PCI, statement, minimum, batch, authorization, gateway.
• Is there a contract term? What is the early termination fee and how is it calculated?
• Is the hardware owned, financed, or leased? Is it locked to your processing?
• Do you support least-cost debit routing, and is it enabled by default?
• What is the chargeback fee, and do I keep it if I win the dispute?
• How and when are funds deposited? Is there a reserve or rolling hold?
• Can I see a sample statement from a business like mine, and can I get a rate review after six months?

The bottom line

Flat-rate pricing is the right default for small and new businesses: predictable, cheap to start, and only slightly more expensive than the alternatives at low volume. As you grow — particularly past $15,000–$25,000 a month, and especially if debit is a big share of your sales — interchange-plus almost always wins, and the savings compound every month. Whatever you are quoted, ignore the headline number, add up every fee, model it against your real card mix and ticket size, and compare effective rates on a real month of your own transactions. That one habit is worth more than any negotiation tactic.