Merchant Account Fees Explained

You finish an $800 HVAC repair on a Friday afternoon. The compressor’s swapped, the system’s humming, and the homeowner taps her card on your phone before you’ve even packed up the van. The job’s done. But when the money lands in your account, it isn’t $800. It’s $776.80. Somewhere between her tap and your bank, about $23 vanished.

Where did that $23 go? Who took it? And — the question that actually matters — how much of it could you have kept?

That $23 is your merchant fees, and most field service pros pay them every single day without ever knowing what they’re made of. This guide breaks down the full anatomy of a merchant account: what you really pay to accept a card, which fees are negotiable, which are fixed by forces you can’t touch, and how to read a statement so the next surprise charge doesn’t blindside you.

What Are Merchant Account Fees?

Merchant account fees are the costs you pay to accept credit and debit card payments. Every card transaction passes through three parties before the money reaches you, and each one takes a slice. According to NerdWallet (2026), the all-in cost typically runs 1.5% to 3.5% per transaction — which is exactly why your $800 job netted around $777.

Here’s the part nobody explains: that percentage isn’t one fee. It’s three layers stacked on top of each other:

1. Interchange — paid to the bank that issued your customer’s card
2. Assessments — paid to the card network (Visa, Mastercard, Amex)
3. Processor markup — your payment processor’s cut

Two of those three are completely out of your control. The third — the markup — is where your money actually leaks. Knowing the difference is the whole game.

The Three Layers of Every Transaction Fee

Interchange Fees

Interchange is the biggest chunk, and it goes to the issuing bank — the bank that gave your customer their card. The catch: the rate depends entirely on what kind of card she pulls out of her wallet.

• Debit cards (large issuers): roughly 0.05% + $0.21 — dirt cheap, thanks to federal regulation (the Durbin Amendment)
• Standard Visa consumer credit (card-present): about 1.15%–1.65% + $0.05–$0.10
• Rewards and premium credit cards: 1.65%–2.40% + $0.10 — those airline-miles cards cost you more
• American Express: roughly 2.3%–3.0% effective for small merchants — the most expensive of all

This is why your fees feel random. When a customer pays with a debit card, you barely notice. When the next one pays with a premium travel-rewards card, you eat a bigger cut. Same invoice amount, different fee — and now you know why. Interchange is non-negotiable. No processor can lower it; the card networks set it twice a year.

Assessment Fees

Assessments go straight to the card networks themselves — Visa, Mastercard, Amex. These run about 0.12% to 0.17% of your volume and, like interchange, are non-negotiable. Every processor pays the exact same assessment rate. Anyone who claims they can discount this is selling you something.

Processor Markup

Here’s the one that matters. The processor markup is your payment processor’s profit — the slice they add on top of interchange and assessments for moving the money and giving you the tools to accept it. This is the only layer you can negotiate or shop around.

• Interchange-plus pricing: markup of 0.10%–0.50% + $0.05–$0.15 per transaction
• Flat-rate pricing: an all-in 2.6%–3.5% + $0.05–$0.30 that bundles all three layers into one number

When someone tells you to “shop around for lower processing fees,” this is the only layer they can actually move. Interchange and assessments are fixed costs every processor pays identically.

Pricing Models: Flat-Rate vs. Interchange-Plus vs. Tiered

How a processor packages those three layers determines what you pay — and how much you can see.

Flat-rate pricing charges one simple number for every transaction. Stripe (2026), for example, charges 2.9% + $0.30 for online payments and 3.4% + $0.30 for manually keyed ones. Square (2026) runs 2.6% + $0.15 in person and 3.3% + $0.30 online. PayPal (2026) sits at 2.89% + $0.29 online. The appeal is predictability — you always know your cost, and there are no surprise monthly bills.

Interchange-plus pricing shows you the actual interchange and assessment costs, then adds a clearly stated markup on top. It’s the most transparent model and the cheapest at higher volume — but it usually comes with monthly account fees, so it only pays off once you’re processing real money.

Tiered pricing sorts your transactions into “qualified,” “mid-qualified,” and “non-qualified” buckets — and conveniently routes most of your cards into the expensive bucket. It sounds simple and almost always costs the most. Avoid it. If a processor can’t tell you a clear percentage, walk.

This is also where your invoicing tool comes in. When you accept card payments through your invoices, the pricing model your processor uses determines your effective rate — so the choice matters more than most people realize.

What You Really Pay on a $200, $500, and $1,000 Invoice

Ranges like “1.5% to 3.5%” are useless when you’re staring at an actual invoice. Here’s the real math across three common job sizes and three pricing setups. (Interchange-plus modeled at 2.1% + $0.10, a realistic blended rate for a mid-volume contractor.)

On a single $1,000 job, the gap between Square’s flat rate and interchange-plus is $12.20. Run a few of those a week and it adds up to real money by year’s end. But notice the trade-off: interchange-plus only wins here because we ignored its monthly fees. At low volume, those fees erase the savings — which is the whole decision you’ll make later in this guide.

The Monthly Fees You Might Be Missing

The per-transaction cut is only half the story. Traditional merchant accounts pile on fixed monthly charges that flat-rate processors usually fold into their rate. These are the fees sprung at the worst moment — when you open a statement and the math doesn’t add up.

• Monthly account/statement fee: $5–$20/month
• PCI compliance fee: $75–$150/year (or $5–$15/month bundled). Square and Stripe bake this into their flat rate; traditional accounts often bill it separately
• Chargeback fee: $20–$35 per dispute — plus you refund the full transaction. A single disputed $800 job can cost you $835
• Gateway fee: $5–$25/month
• Batch/settlement fee: $0.05–$0.25 per batch
• Early termination fee: $250–$500 — the reason you should avoid long-term contracts

Red flag: typical monthly fixed fees run $30–$50/month, but poorly structured accounts hit $80–$150/month before you’ve processed a dime. If your statement shows more than $80 in monthly fixed fees, you’re overpaying — start shopping.

Understanding your full credit card processing fees — both the per-transaction and the monthly layers — is the only way to compare processors honestly.

Flat-Rate or Interchange-Plus: Which Is Right for You?

The honest answer depends entirely on your card volume.

Under $100K/year in card volume → flat-rate wins. A solo freelancer running $30,000/year through Square pays an effective rate around 2.66%. The same freelancer on a traditional merchant account — once you add monthly and PCI fees — ends up near 3.6%. At low volume, flat-rate’s lack of fixed fees beats interchange-plus every time.

$300K+/year in card volume → interchange-plus saves real money. Picture an HVAC contractor running $300,000/year in card payments. On Square’s flat rate (~2.9%), that’s $8,700/year in processing. On an interchange-plus deal at ~2.1% + $40/month, it’s about $6,780/year — a savings of $1,920 a year. That’s a real chunk of a tech’s annual income, recovered just by switching pricing models.

The decision trigger: once you cross roughly $100K–$200K/year in card volume, sit down and run the math. Below that line, keep it simple with flat-rate. Above it, interchange-plus usually wins.

What You Can (and Can’t) Control

Stop fighting the fees you can’t change, and start working the ones you can.

You can control:

• Your pricing model — switch from flat-rate to interchange-plus once your volume justifies it
• Chargebacks — clear invoices, signed estimates, and detailed records prevent disputes that cost $20–$35 each
• Your processor — shop the markup; it’s the only negotiable layer
• Negotiating the markup — once you’re above ~$10,000/month in volume, processors will talk

You can’t control:

• Interchange rates — set by Visa and Mastercard, updated every April and October
• The card type your customer uses — debit, rewards, or Amex, that’s their wallet, not your call
• Assessment fees — every processor pays the networks the same rate

When someone tells you “payment processing is just another fee I can’t control,” they’re half right. The interchange and assessment layers? Fixed. The markup and your chargeback rate? Yours to manage.

Does Your Invoicing App Take a Cut?

This is the grievance you hear most from field service pros: the app takes a cut of my payment. It’s worth being precise here, because the fear is usually misplaced — and sometimes dead on.

Merchant fees go to the card network ecosystem — the issuing bank, the network, and your processor. That’s interchange + assessments + processor markup. None of it goes to your invoicing software, unless the software inserts its own percentage on top. Some apps do exactly that, skimming a point or two from every payment as the price of using their “built-in” payments. That’s the cut that stings — it’s pure overhead, layered on top of the fees you already pay.

A well-built invoicing tool doesn’t do that. It routes the payment through your processor at your negotiated rate and takes nothing from the transaction. Pronto Invoice works this way: you connect your own Stripe or PayPal account, your customer pays through your invoice link, and the money flows to you at your rate. Pronto never takes a percentage of your payment — no markup, no surprise account fees, no games. You look professional, you get paid on the spot, and the only fees you pay are the ones going to the bank and network that you’d pay anyway.

Payment links sent directly from your invoice are the fastest way to get paid — and when your invoicing tool doesn’t skim the transaction, more of that money is yours.

Frequently Asked Questions

Are merchant fees tax-deductible? Yes. Merchant and payment processing fees are an ordinary, necessary business expense, fully deductible on your taxes. Keep your monthly statements — those fees add up to a real deduction over a year.

Why does my fee vary from invoice to invoice? Two reasons: the card type (a debit card costs you far less than a premium rewards credit card) and whether the payment was card-present (tapped in person) or card-not-present (keyed in or paid online, which carries a higher rate). Same dollar amount, different fee — it’s the card, not a glitch.

Can I pass merchant fees to my customer? Often yes, through a surcharge or convenience fee — but check your state law (a few restrict or ban it) and the card network rules, which cap credit card surcharges at roughly 3%–4% and prohibit surcharging debit cards entirely. Disclose it clearly before the customer pays.

When do interchange rates change? Visa and Mastercard update interchange twice a year, in April and October. If your fees shift slightly around those months, that’s why.

Is ACH cheaper than cards? Usually, yes. ACH bank transfers typically run 0.5%–1.5% or a flat fee per transaction — much cheaper than cards on big invoices. See the full ACH guide for small business for when it makes sense to steer customers toward bank transfer instead of card.

The Bottom Line

That $23 off your $800 job wasn’t random, and it wasn’t all unavoidable. Interchange and assessments — most of it — are fixed costs every business pays. But the processor markup, the junk monthly fees, and the app that quietly skims your payment? Those are yours to cut.

Know your volume. Pick the right pricing model. Read your statement line by line. And use an invoicing tool that doesn’t add its own toll on top of the fees you already owe.

Pronto Invoice lets you send professional invoices from your phone and get paid through your own Stripe or PayPal account — no markup on your payments, no surprise account fees, no games. You keep what’s yours.