Got a complex question regarding markov chain modelling.

I'll start off with an example. Say you own a credit card and you can only ever be in 3 states.

1)non-user - you're currently not using your credit card

2)full payer - you pay off your balance in full each month

3)partial payer - you only pay some of your balance off eg. 50%, 60% etc.

I'm not having any problems calculating the probabilities of moving from one state to the next. i just dont know how i would use these probabilities to calculate someone's expected outstanding balance on their credit card.

Any ideas or help?

Much appreciated