As announced on our blog, we have implemented support for new billing cycles. In addition to monthly billing cycles, Zendesk now offers quarterly, biannual and annual billing cycles. And we've built in an incentive. By selecting quarterly billing cycles, we provide a 3% discount. For the biannual cycle it's 6%, and for the annual cycle it's a 10% discount. 

A Zendesk month is 30 days, and thus a Zendesk year is 360 days.

Be aware that the new billing cycles introduces a few changes to how upgrades and downgrades are handled.

If you decide to upgrade your plan while there are more than 30 days left of your current billing cycle, you will be charged an upgrade fee, corresponding to the price difference between your current and the new plan for the remaining days of your billing cycle. This also means that users of the monthly billing cycle will never get charged an upgrade fee. A plan upgrade is considered an upgrade if the plan you are changing to is larger than the plan that was in use at the execution time of the last Zendesk billing.

There will be no downgrade refunds, or refunds for months unused when canceling an account