For a B2B company invoicing $2,500 at a time, interchange plus (also called pass-through pricing, where you pay the real card cost plus a disclosed markup), paired with Level 2 and Level 3 data on business cards and an ACH option on the invoice, is the setup to compare against flat rate. In NPS’s study, a model finds pass-through costs less than flat rate for invoice payments. A flat-rate provider charges the same percentage on every invoice and often adds an invoicing fee on top. This guide shows the dollars on one $2,500 invoice, explains why business cards narrow the gap, and says when flat rate is still the simpler or cheaper choice.
Pricing model showdown
Flat rate vs. interchange plus on invoices
- How is the rate set?
- Flat rateSame percentage on every invoice
- Interchange plusActual interchange and network fees plus a disclosed markup
- Do you benefit from Level 3 data?
- Flat rateNo, one percentage regardless of data sent
- Interchange plusYes, lower interchange earned by correct data is passed through
- Cost on invoices vs. other channels
- Flat rateOften adds an invoicing fee on top
- Interchange plus19% to 31% less than flat rate across tickets from $15 to $2,500
- Best for whom?
- Flat rateVery low volume or brand-new businesses
- Interchange plusBusinesses processing over $25,000 a month and B2B companies
In NPS’s study, a model finds invoice payments show the largest savings of any channel on pass-through.
The short answer
- On a $2,500 invoice, the fee is large in dollars. At Square’s 3.3% plus 30 cents for invoices, one invoice costs $82.80 to collect by card.
- Stripe Invoicing adds 0.4% on top of its card price, per Stripe’s own pricing page (read November 13, 2026).
- In NPS’s 2026 pricing study, a model finds invoice payments show the largest savings of any channel, 19% to 31% less on pass-through across tickets from $15 to $2,500.
- Business cards cost more, which narrows the gap. Level 2 and Level 3 data can lower what business cards cost.
- ACH, a bank-to-bank payment, can cost less than a card on a large invoice, so ask what ACH costs, if the buyer will use it.
What a $2,500 invoice costs by card on a flat rate
Start with arithmetic you can check yourself. NPS’s 2026 pricing study quotes the published prices of the two largest flat-rate providers, accessed in October 2026. Square charges 3.3% plus 30 cents for online payments and invoices. Stripe charges 2.9% plus 30 cents for card processing, and its Invoicing fee adds 0.4% per paid invoice. Stripe also adds 0.5% for manually entered cards, meaning card numbers typed in by you rather than entered by the customer.
On a $2,500 invoice, 3.3% is $82.50 and the fixed fee is 30 cents, so Square’s price comes to $82.80. Stripe at 2.9% plus 30 cents plus the Invoicing fee works out to 3.3% plus 30 cents, or $82.80. If a customer calls and you key the card in on Stripe, add another 0.5%, which is $12.50 on that invoice.
Multiply that by your month. Twenty invoices of $2,500 is $50,000 a month in volume, and roughly $1,656 to $1,706 in card fees at those prices, before disputes and other add-ons. That is arithmetic on the published prices, not a prediction of your bill. The point is that at B2B ticket sizes the percentage is the whole story, and the 30 cents hardly matters.
One $2,500 invoice
What one $2,500 invoice costs by card
- Square invoices$82.80Square invoices3.3% plus 30 cents
- Stripe invoices$82.80Stripe invoices2.9% plus 30 cents plus 0.4% Invoicing fee; add $12.50 more if you key the card in
Why interchange plus can cost less on the same invoice
A flat rate bundles three costs: interchange paid to the bank that issued the buyer’s card, assessments paid to the card networks, and the provider’s markup. Interchange plus pricing separates them. You pay the actual interchange and network fees for that card, and then a markup written in your agreement. NPS explains the model in its guide to four merchant account pricing models and recommends it for businesses processing over $25,000 a month and B2B companies.
The difference shows up on cards that are cheap to accept. Under federal rules (the Durbin Amendment, put into effect as Regulation II), interchange on debit cards from large banks is capped at 0.05% of the sale plus 21 cents, with a 1 cent fraud adjustment. On a $2,500 sale that cap is about $1.47. A flat-rate provider charges the full percentage on that card anyway.
The cap covers debit cards from large banks only. Debit cards from smaller banks are exempt and cost more, and the Federal Reserve has proposed lowering the cap in a proposal the study says is unresolved. So the cap is a reason to look at your card mix, not a number to count on for every invoice.
What the study found for invoices and larger tickets
The study is “The Flat-Rate Tax,” by Allen Kopelman, the CEO of NPS. It is a cost model built on published rate schedules, not a survey, and it was written by a processor that sells pass-through pricing. Read it as a reason to ask for a quote, not as proof of your savings. Link: NPS’s 2026 pricing study.
For invoices and payment links the study uses a flat-rate benchmark of 3.3% plus 30 cents, which is Stripe plus its Invoicing Starter fee or Square’s invoice price. It says businesses selling online or by invoice pay 19% to 31% less in processing costs on pass-through than on flat rate, across average tickets from $15 to $2,500. It reports that invoice payments show the largest savings of any channel in its model. For one example, it says a business collecting $50,000 a month through invoices at a $150 average ticket keeps about $6,100 a year by moving from flat rate to pass-through.
At $2,500, the study assumes only about 10% of card payments are debit, against 25% at a $150 ticket. That means the debit effect is smaller at your ticket size. What helps at $2,500 is different: the card mix on invoices and the data you send with each payment.
Business cards, and why the gap can be narrower
B2B buyers often pay with corporate cards, purchasing cards or company credit cards. Those cards carry higher interchange than a basic consumer debit card. The study’s model says so directly: business and commercial cards can cost more, which narrows the gap, but it also notes that many small businesses pay invoices with debit cards and flat-rate providers often add invoicing fees. In its model, invoice payments still show the largest savings of any channel.
Young companies pay with debit more often than you might expect. The study says young businesses often pay B2B invoices with a business debit card because they do not have a company credit card yet. So the right question is not what a typical B2B card costs but what your buyers actually use. Ask your processor for a report of invoices by card type.
If your buyers are large companies paying with purchasing cards almost every time, the savings from pass-through will be smaller, and the data side of the job matters most. That is where Level 2 and Level 3 come in.
Level 2 and Level 3 data on business cards
Level 2 and Level 3 are extra details sent with a card payment: items such as sales tax and a customer code at Level 2, and line items, quantities, invoice and purchase order numbers, freight and duty at Level 3. When the card is a business, purchasing or fleet card and the data is right, the payment can qualify for a lower interchange rate. NPS covers this in its guide to Level 2 and Level 3 processing.
NPS also says Visa tightened its rules in 2024 with its Commercial Enhanced Data Program, so generic or repeated placeholder values, such as the same purchase order number on every payment, no longer qualify. The data has to be accurate and tied to the real invoice.
Card data levels
What Level 2 and Level 3 data include
| Data level | What you send | What qualifies |
|---|---|---|
| Level 2 | Sales tax and a customer code | Business, purchasing or fleet cards |
| Level 3 | Line items, quantities, invoice and PO numbers, freight and duty | Business, purchasing or fleet cards |
This matters for the flat-rate comparison because a flat-rate provider charges the same percentage with or without that data, so you never see a benefit from sending it. With interchange plus, the lower interchange flows to you. Ask any provider: How is Level 3 data created? Is it generated from my invoice automatically? Which of my payments qualified last month?
ACH: the other way to collect a $2,500 invoice
ACH is a bank-to-bank transfer. NPS’s ACH guide says optimized ACH is often in the range of 0.50% to 1% with a cap, compared with 2.5% to 3.5% for credit cards on its page, and that ACH has fewer chargebacks because it does not follow card-network dispute rules. On a $2,500 invoice, the difference between a card fee of $82.80 or more (3.3% of $2,500 is $82.50, plus 30 cents) and an ACH fee in that range is large enough to change which payment method you push.
Plenty of B2B buyers will pay by ACH if you make it easy. Put an ACH option beside the card option on every invoice. Some sellers use a cash discount or dual pricing so the buyer sees a lower price for paying by bank transfer. NPS describes that approach in its guide to dual pricing. How you may structure and word it depends on the rules that apply to you, so set it up with a provider that explains them.
One more reason to offer both: buyers have different needs. Some prefer a card to earn rewards or to stretch their cash. NPS’s ACH guide says customers pay bills in eight days or less when they can pay through a secure link. Read the whole ACH optimization guide before you decide.
When flat rate is still the better choice
The study is honest about this, and so should you be. Flat rate is sometimes the better deal. It names in-person businesses with very small tickets, around $15 and under, and brand-new businesses with very low volume. Neither describes a company that bills $2,500 at a time.
There are still B2B cases where flat rate makes sense. You might send one or two invoices a month. Your buyers might pay almost entirely by ACH or check, so card cost hardly matters. You might be so new that you have no statements for a quote. NPS’s pricing guide lists flat rate as best for merchants under $10,000 a month. If one $2,500 invoice a month is your entire card volume, the savings are tiny in dollars, and a no-contract flat-rate account is fine.
Another case is when a flat-rate provider is built into your invoicing or accounting software and the convenience is worth the cost. That is a real tradeoff. Count the hours you spend reconciling payments by hand, and compare with the dollars you would save.
The invoicing features that save time and cash
Cost per payment is only part of B2B card processing. NPS describes Smart Invoicing as covering one-time invoices, split payment project billing, monthly retainers and subscription plans, with branded payment links, automatic reminders, early-pay discounts, late-fee rules, a customer portal, role-based permissions and a two-way QuickBooks Online sync. It also says unlimited users are included, which can matter if several staff members send invoices.
Ask every provider the same questions about the workflow:
- Can the buyer pay one invoice by card, ACH or a split between them?
- Does the invoice carry the PO number, and is Level 3 data created from it?
- Does the payment sync to my accounting system and mark the invoice paid?
- What does a manually keyed card cost?
- What do I pay for a dispute, and are fees returned if I win?
- Is there a per-user charge?
Also look at how you will be paid. A hold on funds can hurt a company that depends on a few large invoices. Ask each provider when funds are released and under what conditions they can be held. The study notes Stripe’s dispute fee of $15, plus $15 to respond manually, refunded if you win.
Questions to ask
Ask every provider these questions
- Can the buyer pay one invoice by card, ACH or a split between them?
- Does the invoice carry the PO number, and is Level 3 data created from it?
- Does the payment sync to my accounting system and mark the invoice paid?
- What does a manually keyed card cost?
- What do I pay for a dispute, and are fees returned if I win?
- Is there a per-user charge?
How to get a quote you can trust
Gather your last three months of paid invoices: count, total, average, share paid by card versus ACH, and the card types if you can see them. Then ask each provider to price that exact set, all fees included, and show the dollars.
NPS offers a free statement review. See how much you are really paying on Stripe, Square, PayPal or QuickBooks and the best B2B payment gateway for manufacturers and distributors for more detail.
When you compare quotes, divide total fees by total card sales to get an effective rate. A fair comparison counts monthly fees, ACH fees, dispute fees and software fees, not just the card rate.
For the full picture across every sales channel and average ticket, read our guide to cheapest payment processing in 2026.
Who wrote this, and where NPS fits
Nationwide Payment Systems (NPS) publishes this guide. We are a payments company based in Fort Lauderdale, Florida, in business since 2001, and we sell merchant accounts and invoicing software, so we are not neutral. We offer interchange-plus pricing, Level 2 and Level 3 processing, ACH, a payment gateway and Smart Invoicing, and we also offer flat-rate options. We do not publish a price list, because pricing depends on volume, ticket size, card mix and risk. The study we cite was written by our CEO. Browse more in our payments guides and our guide to B2B payments.
We are not the right fit for every company. If you bill very little by card, you want an instant self-service sign-up, or your buyers pay almost entirely by check or ACH, a simpler setup will probably suit you better.
Bottom line
For a B2B company invoicing $2,500 at a time, interchange plus with Level 2 and Level 3 data and an ACH option on every invoice is the setup to compare against flat rate. By NPS’s arithmetic on the prices quoted above, a $2,500 invoice costs $82.80 on Square’s 3.3% plus 30 cents, and $82.80 on Stripe’s 2.9% plus 30 cents plus its 0.4% Invoicing fee. In NPS’s study, a model finds invoice payments show the largest savings of any channel. Business cards narrow the gap, and flat rate can win for very low volume or very new businesses. Ask for a quote built from your own paid invoices. If you would like a second opinion on a quote or on your current statement, you can contact our team, and if another setup fits you better, we will say so.
Frequently asked questions
How much does it cost to take a $2,500 invoice by card?
On Square’s published 3.3% plus 30 cents for invoices, quoted in NPS’s study, it is $82.80. On Stripe’s 2.9% plus 30 cents plus its 0.4% Invoicing fee, it is $82.80. Interchange-plus cost depends on the card used.
Is interchange plus cheaper than flat rate for B2B invoices?
Often, but not always. In NPS’s study, a model finds 19% to 31% lower costs for invoice and online sales across tickets from $15 to $2,500. Business cards cost more, which narrows the gap, so test it on your own invoices.
What are Level 2 and Level 3 data?
They are extra transaction details, such as tax, customer code, line items and purchase order numbers, that can qualify business and purchasing card payments for lower interchange. The data must be accurate and tied to the actual invoice.
Why does a flat rate not reward Level 3 data?
A flat rate charges one percentage regardless of the card or the data sent. With interchange plus, the lower interchange earned by correct data is passed through to you.
Should I offer ACH on a $2,500 invoice?
Often yes. NPS’s guide says optimized ACH is often 0.50% to 1% with a cap and has fewer chargebacks. Not every buyer will use it, so offer cards too.
When is flat rate cheaper for a B2B seller?
The study says flat rate can be better for tickets around $15 and under in person and for brand-new low-volume businesses. A seller with only a few card invoices a month may also prefer its simplicity.
Does NPS review my current statement for free?
Yes. NPS offers a free statement review. Send a statement and ask for the math on your own invoices.
