Why does AMEX have CID and CVV

I’m curious as to why they have the 4 digit CID on the front and the 3 digit CVV on the back.

When I first tried using it online I put the 3 digits on the back in and it got declined. Why put it there if you can’t use it?

P.S. It might be worth adding an Amex and Apple category @Liam as we have a lot of users of the former and it looks like Apple will be launching their credit card in the UK in the coming yearish

Bear in mind Amex is big in the USA, so most of this applies there.

The CID is stored in the mag strip, it proves the retailer has your card when they process your payment. In the US magstripe is still very widely used.

The CVV is used when initiating remote purchases.

Some merchants require the actual CID its just how American Express works over here. But many will work with the CVV as well.

My experience is that with my amex the only occasion where I’ve used the digits in the back was when I activated the card on the website.

I have only ever used the cid from the front for online purchases.

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I’ve never once used my CVV , only the CID.


Same for me, Amex themselves are the only ones that have asked for the CVV.


As explained to me by Amex some years ago, the CVV is the 4 digits on the front of the card, and the CID is the 3 digits on the back. They only use the 3 digits on the back themselves as others have pointed out.

I also read somewhere, and I can’t find the source now that there was significance in the fact that 16+3 and 15+4 both equal 19 :slight_smile: