When you leave a company, whether voluntarily, through a lay-off, or because of retirement, you need to make a decision about any money in your qualified retirement plan. You usually have limited control over money in defined benefit or deferred compensation plans, but you do have control over money in 401(k)s, 403(b)s, and other defined contribution plans.
Leaving It There
One school of thought says “take the path of least resistance” and leave your money where it is. Since most Americans are highly mobile and will work for 5-10 employers over their working lives, this can leave many small accounts scattered all over the country.
Taking It Out
If you are like most people, you like to know where your money is, and you like to have control over your hard-earned cash. If this describes you, you may want to move your qualified retirement plan money into a personal IRA account(s). There are (at least) three arguments in favor of this approach.
First, you decide how to invest your retirement money instead of being limited to the choices available under your former employer’s retirement plan. This is very important if for example the former employer put its contributions into its own stock. In addition, if you have qualified retirement plans at multiple companies, the number of investments you have to choose, manage, and understand is often overwhelming. When the money is in your IRA account you (and your financial advisors) make the investment decisions.
Second, if you leave a company (by choice or through lay-off) you may not want your old employer to know about your assets. Privacy is actually one of the main reasons people move their money to personal IRA accounts.
Another, often overlooked, reason is that it can be very difficult and time-consuming to get your retirement money out of a former employer’s plan. You may have to make lots of calls, send multiple emails, and wait for months while your current investments are down or the investments you want to make are rising. Employers have a surprising amount of leeway about when they send your money to your new IRA account. 
Moving Money to a New Employer’s Plan
A final option is moving some or all of the qualified retirement plan money you have scattered around to your new employer’s retirement plan. This may be a good choice, or it may not.
Does the new plan accept rollovers? Are your investment options comparable? How do the investment fees compare? These are just a few questions to ask before rolling over money to your new employer’s retirement plan.
So Now What?
Talk to your financial and tax advisors each time you are considering adding money to a qualified retirement plan. As you prepare to retire or leave a company you should also seek advice about what to do with your pension money—take it or leave it.