Are they adding him to the card or will he simply be an authorized user?

If he's only an authorized user make sure he retains his own cards and occasionally uses them so he maintains a credit history.

As long as he's truly responsible with money and bill paying, and your relationship is strong, there's no reason not to.

Let me just start with saying I am not talking about him running away after borrowing a lot on it

I have an AMEX platinum card which I have had for years, since my single days. Anytime I am buying stuff, be it groceries or gas or something for me, I put it on this card. I use all the points at the end of year to buy Christmas gifts on Amazon. However, we had our second child recently and I am not going out much for errands so my husband has been the one paying for everything using the debit card.

AMEX seems to have a simple form to fill in so that I can add him to my card. If I get him on this card, we can collect points no matter who spends the money. Is this going to have any adverse impact on either of our credit scores or any other issues? We always pay off the CC at the end of the month. TIA.