NEW YORK (CNNMoney.com) - I'm 33 years and am trying to get a handle on planning for retirement. I have two 401(k)s from previous jobs that have about $85,000 in them, plus I've got about $5,000 in the 401(k) at my present job. I contribute 19 percent of my salary to my current 401(k) - which is enough to hit the maximum contribution amount of $15,000 for this year.

My company, however, matches only the first 4.5 percent of salary I put in. A friend of mine says that anything I contribute to my 401(k) beyond the employer's match is a waste, and that I should be putting my money into something else. What do you think?

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- Brian, Raleigh, North Carolina

A waste? I think your friend is being a little harsh to say the least. Yes, it would be terrific if your company matched more than the first 4.5 percent of salary you contribute. But that hardly means the money you stash in your 401(k) beyond the match is a waste.

For one thing, you're still getting a nice little tax break on your entire 401(k) contribution since you're socking away pre-tax dollars. And there's the not-so-insignificant benefit of convenience. By having money taken directly from your paycheck before you have a chance to get your cash-hungry little mitts on it, you're much less likely to fall into the "I meant to save for retirement but never got around to it" trap. With automatic payroll deductions, the money flows into your 401(k) like clockwork. This is about as close to painless saving as you can get.

And let's not forget the reason for investing through a 401(k) in the first place. You're doing this not as some sort of theoretical financial exercise, but to achieve an important real-world goal - namely, to build a nest egg during your career that can support you in retirement. To the extent you can save and invest money year after year in a 401(k), you're much more likely to achieve that goal.

That said, your friend does have a point in that you might want to consider another alternative for at least some of your savings. And the option that probably makes the most sense for someone in your situation is the Roth IRA.

You don't get immediate tax break with the Roth as you do with a 401(k). That's because you contribute after-tax dollars to a Roth. But the Roth does give you a neat tax benefit later on - namely, you don't pay tax when you withdraw your money, provided you meet certain criteria. (For details on how to assure your withdrawals are tax free, as well as income eligibility requirements for a Roth IRA, click here).

I particularly like the Roth IRA for people who are young and have good prospects. The reason is that when you contribute to a Roth, you're taking the tax hit today rather than paying taxes on the earnings in your Roth account in the future.

If you believe your income will rise and push you into a higher tax bracket, then you're paying income tax on your contribution today at a lower rate and avoiding the tax later on when you're in a higher tax bracket. That sort of tax-rate arbitrage, so to speak, is as Martha says, a good thing.

Of course, since we can never be absolutely sure what tax rate we'll face in the future, if for no other reason than the boys and girls in Washington, DC have a disconcerting habit of changing the rules on us.

But by having money both in a 401(k) that will be taxed at whatever rates prevail when you withdraw it and in a Roth IRA where the withdrawals won't be taxed at all, you get to practice what I like to call "tax diversification." You're sort of hedging your bets so all your savings aren't subject to one tax rate. And by having different pots of money that receive different tax treatment, you'll also have more control over your tax bill in retirement. (For more on the concept of tax diversification, click here.)

So I would have no problem, for example, with you contributing to both your 401(k) and a Roth. Since the maximum Roth contribution this year is $4,000 (plus a $1,000 "catch-up" contribution for people 50 and older), you'll be able to fund a Roth and still contribute well beyond the 4.5 percent employer match in your 401(k).

What you definitely do not want to do, however, is cut back on your 401(k) contribution and then fail to go through with the Roth. You'd be surprised how many people get the basic idea of tax diversification down, but never quite get around to writing the check for the Roth. And that, as your friend says, would be a waste.

If you think there's a chance you might fall into that group, you might consider opening a Roth account with one of the many mutual fund companies that will automatically pull money from your checking account each month and invest it in your Roth account.

And, of course, there's absolutely nothing wrong with continuing to sock away the same 19 percent in your 401(k) and, if you can swing it, come up with additional savings to fund the Roth. You might have to deny yourself a few indulgences to pull off such a move, but you'll dramatically increase your chances of having a comfortable retirement when you're ready to call it a career.

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