what is the smallest payment you are allowed to make on a credit card ? (on the web) is there a minimum? does it differ according to USA/UK, or card type?
I'm not sure of a formal limit, but you are charged a flat fee per transaction by your merchant account provider. It depends on where you get your merchant account, but $0.25 per transaction is pretty typical if my memory serves me right.
There is no minimum. As a business, as stated, you are charged on a per transaction bases normally with a percentage and a flat transaction fee. US is going to be much cheaper than UK. But no matter what you do expect a transaction fee of at least $.25 / transaction Plus a 1.7% and up processing fee depending on how you take the card. Paypal also offers a micro-payments option for small tickets, that as far as I have ever seen is unbeatable, but it is paypal. Are you looking at this from a consumer point of view or a someone looking to accept small payments?