When you leave an old job, one of the most important considerations that you have to take is what to do with your 401k account. When leaving a company, you need to be sure that you rollover the account properly. When looking to roll over a 401k, you can either roll it over into another 401k account or into an IRA. If you do not roll the money into one of these accounts, you may end up being taxed at your minimum tax rate and you could also incur penalties up to 10% of the amount of money that is withdrawn.