 An in-service rollover allows you to move money out of your 401k into an IRA. You do this with no charge. You do this with no taxes. You continue to have your 401k. You continue to work your job. You continue to fund your 401k. But this allows you to take a block of money, if you choose to, out of your 401k into an IRA. Why would you do this? Well, perhaps you're not happy with these account options you have available in your 401k.