A monthly minimum is a floor on processor revenue. If the markup your account produces in a month sits below the contracted dollar amount, the processor bills the difference as a true-up. Interchange and network assessments do not usually count toward that floor: they are pass-through, and the minimum is protecting the processor's own take. High-volume months ignore it. Low-volume months, seasonal troughs, and idle merchant IDs pay it. Model the slowest month you actually have before you sign, because that is the month the clause was written for.
The floor is on markup, not on card volume
The clause prints as "monthly minimum," "minimum discount," "minimum processing fee," or "discount shortfall." It is not a tax and not a card-network assessment. It is a contractual promise that the processor will collect at least $X of its own fees that month.
Some applications phrase the same idea as a volume gate ("you must process $10,000 a month"). That is usually the fee floor restated as sales. If the quoted markup is 25 basis points, a $25 minimum is $10,000 of volume, assuming per-item fees do not count. Ask which version you signed.
Three questions decide what you owe:
- What is the dollar floor? Applications print $10, $25, $35, or $50. Treat any figure as a quote, not an industry average.
- What lines count toward it? Percentage markup and per-item fees often count. PCI program fees, statement fees, batch fees, gateway fees, and equipment leases usually do not. Interchange and assessments should not, because they are not processor revenue.
- Is it per MID? A second location, a seasonal patio, or a gift-card account can carry its own floor even if the main shop is busy.
If you cannot get those three answers in writing, you cannot model the clause. The merchant statement will show the true-up after the fact, under a name that may not match the application.
A worked month (illustrative)
Label every dollar here illustrative.
A shop processes $4,000 in card volume across 80 settled sales. Pricing is interchange-plus, 15 basis points plus $0.10 per item, with a $50 monthly minimum. Interchange and assessments are pass-through and do not count toward the floor.
| Line | Amount |
|---|---|
| Percentage markup (15 BPS of $4,000) | $6.00 |
| Per-item (80 x $0.10) | $8.00 |
| Markup that counts toward the floor | $14.00 |
| Monthly minimum | $50.00 |
| True-up billed | $36.00 |
Interchange, assessments, PCI, statement, and batch still bill on top. The $36 is extra markup so the processor's take reaches $50, not a replacement for those lines.
If every month looked like this, the true-up alone would be $432 a year ($36 x 12). On $48,000 of annual card volume that is 0.90 percent of volume, sitting in the numerator of effective rate next to interchange.
Same shop in a busy month, $40,000 volume, 800 sales:
- 15 BPS = $60.00
- 800 x $0.10 = $80.00
- Qualifying markup = $140.00
- True-up = $0
The clause did not disappear. It just did not fire. That is why a merchant who looks only at July statements concludes they "do not have a minimum."
Why slow months, not busy ones, are the design
Processors still run statements, risk monitoring, and sponsorship when you process $400. The floor is their break-even on a quiet MID, a real cost, not automatically junk. It becomes a problem when the floor is sized for a different business than the one you run.
The months that pay it:
- Seasonal troughs. A pool shop, a patio MID, a holiday-retail pop-up that keeps the account open in February.
- New shops. The first 60 to 90 days of card volume often sit under the floor even if the quote assumed year-two volume.
- Second locations. The busy store does not subsidize the slow store's minimum if each MID has its own floor.
- Mix shifts. A month that is cash-heavy, invoiced, or ACH-heavy can drop card volume under the floor even though the register is fine.
A closed-for-winter MID with $0 card volume and a $35 minimum still owes $35, plus every other monthly extra that does not care about volume. Five such months are $175 of true-up before PCI or statement fees. Leaving the MID open "just in case" is a decision with a price.
The U.S. Chamber of Commerce (4 Jun 2026) describes typical processing fees as 1.5 percent to 3.5 percent of the transaction plus a per-item fee, and it flags monthly minimums as extras sitting outside that headline. Treat the range as typical, not a quote. A quiet month plus a floor is how a merchant who "should" sit inside it prints above it.
What the minimum is not
- A statement fee is a charge to produce the bill. It does not usually count toward the minimum, and the minimum does not replace it.
- A PCI program or non-validation fee is a different product. Same rule: extra, not a credit against the floor.
- A batch fee is a per-close or monthly settlement charge.
- An equipment lease or wireless fee is rent on hardware.
- Interchange is the issuing bank's cut. If a statement appears to fold interchange into "discount" and then applies a minimum to that bundle, ask for the waterfall. A floor that includes pass-through costs is a different deal than a floor on markup.
Those extras are the junk-fee audit if they do no work. The monthly minimum is contractual even when it is doing work. Both belong in effective rate.
Pricing model does not erase the clause. Interchange-plus makes the true-up easy to see because markup is itemized. Tiered and blended statements can bury a shortfall inside "discount." Some flat-rate programs skip a separate minimum because the blended rate already over-collects on a quiet mix; some still bill an account fee that behaves like a floor. Read the application, not the sales story about the model.
How the floor moves effective rate
Effective rate is total processing fees divided by gross card volume. A true-up is a processing fee. Leave it out of the numerator and every comparison you run against a processor with no floor is incomplete.
Illustrative, same $4,000 month. Assume interchange and assessments total $72 (1.80 percent), qualifying markup is $14, the true-up is $36, and monthly extras (PCI, statement, batch) total $22.
| Bucket | Amount |
|---|---|
| Interchange and assessments | $72.00 |
| Qualifying markup | $14.00 |
| Monthly-minimum true-up | $36.00 |
| Other monthly extras | $22.00 |
| Total fees | $144.00 |
| Effective rate ($144 / $4,000) | 3.60% |
Without the true-up, the same month is $108 / $4,000 = 2.70%. The floor added 90 basis points in a month the quote never mentioned.
Busy-month effective rate will look fine. The comparison that matters is twelve months of true-ups against twelve months of volume, not the July PDF.
What to model before you sign
Ask for the clause in the merchant application, not in a verbal. Then run three volumes through it: last year's worst month, a typical month, and a zero-volume month (seasonal close or a stalled opening).
- Compute qualifying markup at the quoted BPS and per-item on each of those three volumes.
- Subtract from the floor. If the result is positive, that is the true-up. If it is zero or negative, the floor is idle.
- Add the lines that do not count: PCI, statement, batch, gateway, wireless. They still bill.
- Annualize the true-ups, not the floor. A $50 minimum that fires four months is $200 a year of extra markup, not $600.
- Check per-MID. If you are boarding two accounts, model two floors.
A modest floor on a shop that clears it eleven months a year is cheap insurance the processor priced in public. A $50 floor on a $2,000-a-month side location is a second pricing model hiding in the contract. Neither is good or bad until you do the arithmetic.
If you are already on a book, pull twelve statements and highlight every minimum, discount-shortfall, or true-up line. Sum them. That sum, divided by annual card volume, is the basis-point leak the quote omitted. If the names are opaque, run the analyzer and read the as-billed sheet.
What to do this month
- Find the clause and the dollar floor. If the application is silent, ask in writing whether one exists and what it is called on the statement.
- Confirm which lines count toward it. Get "interchange excluded" in a sentence, not a shrug.
- Recompute last month two ways: with the true-up and without. The gap is the clause.
- If you have a seasonal or second MID, decide whether the account should stay open in the trough. Closing it has its own cost (re-underwriting, new equipment, a new MID). Price both paths.
- If the floor is the reason your quiet months look expensive, negotiate the number, the counting rule, or a seasonal waiver. Do not negotiate the July rate and ignore January.
The goal is a floor you can see, sized to the volume you actually run, sitting inside effective rate instead of underneath the quote.
FAQ
What is a monthly minimum fee on a merchant account? A monthly minimum is a floor on processor markup. If the qualifying fees your account produces that month fall short of the contracted dollar amount, the processor bills the difference as a true-up. Interchange and network assessments usually do not count toward the floor.
Does interchange count toward the monthly minimum? Usually no. Interchange is paid to the issuing bank and assessments to the networks. The floor is typically on the processor's own take. Confirm the counting rule in the application. A floor that includes pass-through costs is a different, and usually worse, deal than a floor on markup.
When does a monthly minimum actually bill? Only in months when qualifying markup sits below the floor. Busy months show a $0 true-up, which is why a July statement is a bad sample. Slow, seasonal, new, and second-location months are the ones that pay it.
Is a monthly minimum the same as a statement fee or a PCI fee? No. Statement, PCI, batch, gateway, and equipment lines are separate products. They usually do not count toward the floor, and the floor does not replace them. You can owe the true-up and those extras in the same month.
How do I calculate what a monthly minimum will cost? Compute qualifying markup at your quoted basis points and per-item fee on a slow month. If that number is below the floor, the difference is the true-up. Annualize only the months it fires, then put the total in the numerator of effective rate.
Can I get a monthly minimum waived? Sometimes. Providers will lower the floor, count more lines toward it, or waive it for a seasonal trough. Get the change in the merchant application. A verbal 'you process enough that it will never hit' is not a waiver.
Sources
- U.S. Chamber of Commerce, "How to Calculate Credit Card Processing Fees," 4 Jun 2026: https://www.uschamber.com/co/run/finance/calculate-credit-card-fees
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