In most cases, there is no limit on the amount you may transfer or roll over into an IRA. You are simply moving the money from one type of retirement plan to another. You may transfer or roll over your IRA regardless of your age. However, if you are 72 or older, you must receive a minimum required distribution from your IRA each year. This should be taken into account in planning your rollover.
Limits do apply to multiple rollover transactions. You may receive an IRA distribution and roll the funds into another IRA once during a twelve-month period. This rule applies to each IRA separately and begins on the date funds are received.