Can the credit be accumulated on my Nespresso account? E.g. if not used for 4 months will the amount of credit be carried to the next month's plan.

Yes. Club Credits can be accumulated for 12 months to buy whenever you want. You do not have to use up your credit every month. In addition, you can also use your credit only partially, it will still carry over. Club Credits will even be valid for up to 12-month, after that we will convert any unused credit into capsules or accessories for you to use.