# What is Merchant category code?

> A merchant category code (MCC) is the four-digit code card networks use to classify what a merchant sells; it affects approval, fees and how issuers treat a prop firm's charges.

- Source: https://pipvalley.com/glossary/merchant-category-code
- Publisher: PipValley - web design studio for prop trading firms
- Updated: 2026-10-03

In a prop firm, the MCC is assigned by the acquirer when the merchant account is set up, based on how the business is described. Prop evaluations do not fit neatly into one category, and acquirers have classified them in different ways, for example under securities-related or digital services codes.

The MCC influences which issuers decline transactions, the interchange rates that apply, which network monitoring programs cover the merchant and whether the merchant is treated as high risk.

Misdescribing the business to get a friendlier code is a serious risk: networks and acquirers treat it as a violation, and it can lead to account termination and listing on industry match files.

## Why it matters

If your approval rate looks low or certain countries decline more often, the MCC is one of the first things to check with your acquirer. Describe your product accurately at underwriting, and make sure the website sells exactly what the merchant account says you sell.