You'll often hear that it's important to save for retirement independently and not simply rely on Social Security to cover your bills. That's because the benefits you receive from Social Security might replace about 40% of your former paycheck if you're an average earner, and most seniors need around twice that much income to maintain the lifestyles they're used to.

Now when it comes to building a nest egg, you have choices. You could put money into a 401(k) plan if your employer offers one, and from there, you may get to choose between the traditional and Roth variety. You could also house your long-term savings in a traditional IRA if you don't have a 401(k) or don't like the idea of saving in one due to the drawbacks involved (like limited investment choices and potentially high fees).

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But if you really want the freedom to do what you want with your savings, then it pays to build your nest egg in a Roth IRA. Here's why.

It's all about flexibility

Retirement plans like IRAs and 401(k)s offer a host of tax benefits. Because of that, the IRS imposes some pretty strict rules.

One rule is that you generally can't let your retirement plan sit untouched and gain value indefinitely. Rather, at some point, you'll be forced to start taking money out of your savings, whether you want to do so or not. Those forced withdrawals are known as required minimum distributions, or RMDs.

RMDs used to kick in starting at age 70 1/2. Now, you don't have to worry about them until age 72. But either way, RMDs can be problematic for a couple of reasons.

First, if you don't need to take money out of your savings, you're forced to do so anyway. That can be frustrating if you're still working and/or if your hope is to leave a large amount of money to your heirs.

Secondly, unless you have a Roth 401(k), RMDs automatically create a tax liability for you. And, they could propel you into a category where you face federal taxes on your Social Security benefits.

That's precisely why it pays to look at a Roth IRA. Roth IRAs are the only tax-advantaged retirement savings plan to not impose RMDs. And so if you're big on flexibility with your money, that perk alone should inspire you to look at a Roth.

Now you may be aware that Roth IRAs have income limits associated with them. But if you earn too much to fund a Roth IRA directly, don't sweat it -- you can always contribute to a traditional IRA and do a Roth IRA conversion.

Don't lock yourself into a withdrawal schedule

The penalty for failing to take RMDs is harsh -- 50% of whatever sum you're supposed to remove from your savings but don't. A better bet, therefore, may be to avoid RMDs altogether.

If you keep your retirement savings in a Roth IRA, you'll get to take withdrawals when you decide you're ready. And that alone makes a Roth IRA worth it.