<prompt> Human: I have an Amex credit card which gets 6 cash back at grocery stores and 3 at gas stations. This averages over 600 per year, and the annual fee is just 75. It would be much easier for my gf and I to split the grocery bills if we each had this card and split the bill when the monthly credit card bill arrived. Currently its a hassle to track our grocery spending and ensure were splitting it evenly. Weve agreed that the card would only be for groceries, gas, and apartment stuff, and it will always be paid off in full. My question is this: will it help her credit score too? its a total deal breaker if only my credit score will be helped.  <response>: Always a bad idea to co-mingle accounts if you are not married. You arent going to get 600yr in rewards and even if you did thats a small reward for the potential of ruining your credit should one of you decide the relationship isnt so sweet down the road. 