What it is
Flat-rate pricing charges the same percentage, and often the same per-item fee, on every card regardless of type. It's common with Square, Stripe and PayPal.
What it costs you
You pay the same on low-cost debit as on premium rewards cards, so the processor keeps the difference. At higher volume that gap gets large.
What to do about it
- Calculate your effective rate
- Compare against interchange-plus quotes
- Revisit pricing as volume grows