The compounding effect of small percentages
A 0.5 percent difference in effective payment rate sounds tiny. On a business doing 500,000 a year in card payments, it is 2,500 — every year, paid out of margin, never voluntarily.
Most SMBs choose a payment provider once at signup and never review the choice. Three years later, their effective rate has drifted up due to product mix, international expansion, or new fee categories the provider quietly added.
Where the drift comes from
Three categories cause most of the drift. International mix increases as the business grows beyond its home market. Average order value drops as new product lines are added. Refund and chargeback rates climb as volume grows.
Each of these shifts the effective rate upward against the headline rate the business signed up for.
What to actually do
Pull three months of payment data, calculate the effective rate (total fees divided by total volume), and compare it to two or three alternative providers using the same data. If you are 0.5 percent or more above the cheapest realistic option, switching is usually worth the friction. If you are within 0.3 percent, leave it alone.