You can easily find your MCC code if you are operating on Stripe via contacting the live chat here.
If you are not on Stripe, reach out to your payment processor to get it.

A MCC (Merchant Category Code) is a 4 digit code the defines the kind of business you are operating so consumer banks know what type of charge is being authorized. Each MCC code is assosciated with a level of risk which impacts your payment authorization rates as well as your alert prices.

0001–1499	Agricultural services
1500–2999	Contracted services
4000–4799	Transportation services
4800–4999	Utility services
5000–5599	Retail outlet services
5600-5699	Clothing stores
5700-7299	Miscellaneous stores
7300–7999	Business services
8000–8999	Contracted services
9000–9999	Government services