All updates made to the SellerChamp subscription plan are prorated and take immediate effect. This means that you are switched over to the new plan right away and the balance is calculated based on the subscription upgrade or downgrade. This balance is either charged (if you upgraded) immediately or is applied as a credit (if you downgraded) towards your next billing cycle.

In addition to the above, the subscription billing cycle/date is also changed to the day when you updated your subscription plan.