Transition to monthly billing
At this time, not all customers can transition to monthly billing. If you're on the new infrastructure, your renewal date is less than 30 days away, and auto-renew is turned off, check the Domain Settings > Billing Information tab in your Google Apps Admin console for a Learn more link to see if you're eligible.
We currently don't offer a way to manually switch billing systems in the middle of your subscription; however, we will begin automatic transitions to the new system in late 2011. The automatic transition to post-pay billing does not have any service or billing impact on customers who have a pre-paid annual contract. If you have selected to auto-renew your annual contract, it will be auto-renewed to the Annual Plan, with monthly payments, once accounts are migrated to the new billing system.