How much will it cost?

There is no hard and fast rule, but NatWest and others quoted a rough figure of three per cent per transaction plus the rental of the swipe machine - £15 - £25 per month - and a one-off set-up fee of £100-£150. If you are going to use the credit card facility to take cards over the phone, internet or by fax then when you apply for merchant status you need to make it clear you want 'customer not present' transactions.

That's the official story, but it's always worth checking whether you're entitled to any better deals. One dentist, who preferred to remain anonymous, negotiated himself a vastly better deal. 'We get 1.4 per cent and 20p from Switch,' he explained. 'The British Dental Association went to NatWest Streamline and negotiated themselves a very good deal, so I used this to leverage HSBC.'

So if you're in any professional association at all, don't be afraid to ask whether there are price breaks available - and as your business grows don't worry about renegotiating rentals. For example, the supermarket chains, petrol outlets and other larger concerns do not pay the full £15 for each swipe machine, volume discounts are available.

A number of different machines are available, but a basic merchant account will come with two; one that plugs into the phone socket and one of the old-fashioned swipe machines (with vouchers) in case your phone line is ever down. If you anticipate a lot of transactions you might have to factor the cost of an extra phone line into your calculations.

Depending on the nature of your business, you might also want to think about accepting American Express (Amex).

This works differently from the basic package in that you need to be apply separately to Amex itself, and the downside is that you will pay a couple of percentage points more per transaction. This leads some people to put in a cost differential for Amex, as Jim Bissett, MD of computer seller EQ Consultants, notes: 'It doesn't seem to put people who have only Amex off - I expect they are used to surcharges!

For even more kudos there's Diners Club, pitched at the more affluent business traveler - again, apply direct to Diners Club and bear in mind that putting the sticker in the window as much as a statement about the kind of company you are as a means of gaining income.