We all know we need to save money for retirement. Roth IRAs are great ways to build your retirement savings, but they aren't for everyone.

In this video from the Motley Fool Live Financial Planning series, longtime Fool retirement and financial planning expert Robert Brokamp discusses the downsides to a Roth IRA. As he explains, the biggest factor is whether you get more value from a tax break now versus tax-free treatment later.

Robert Brokamp: What are the disadvantages of a Roth 401(k)? I would say just in general, the disadvantages of the Roth is that you do not get a tax break today. You do get a tax break in retirement. So it's a question of when do you want the tax break.

If you are in a higher tax bracket today because of your own income or the joint income with your spouse if you're married, then maybe the traditional makes more sense and you wouldn't do the Roth. But if you're in a lower tax bracket and you expect to be in the future tax bracket because you're going to earn more money or expect tax rates to go up, which a lot of people do, then the Roth makes sense and you don't have to do one or the other.

As I've said before on this show, when I can make contributions to my 401(k) at the Fool, about 15% or 20% of it goes to Roth, the rest into traditional. Another thing to know about the Roth 401(k) is if you receive a match, the match actually goes into a traditional account. So if you have a Roth 401(k) with the match, you actually have two buckets. There's your contributions to the Roth that will all grow tax-free. The contributions or the match will grow tax-deferred, and when you take that out, that will be taxable. Depending on how good the website is for your 401(k), it's easy or not so easy to see what that split is between those two.