Rules and conditions
Offer a method only where it makes sense, and add a fee where you need one.
Rules make a payment method available only in the circumstances you choose: above or below a given cart total, in chosen countries, for chosen product categories, or for chosen customer roles. A method can also carry a fixed or percentage fee.
What you can condition on
- Cart total, above a minimum, below a maximum, or between the two.
- Country, from the billing or shipping address.
- Product category in the cart.
- Customer role, which is how a wholesale-only method is done.
Fees
A method can add a fixed amount or a percentage to the order. The fee is part of the total, so the unique payment code and everything that matches against it still work normally.
A method that disappeared
Rules are the usual reason a method is missing at checkout when it looks switched on. Check the cart against every condition on the method before looking elsewhere.