We're told we're supposed to save for retirement, which generally means setting money aside each month in an IRA or 401(k). But if there's one mistake you don't want to make with regard to your retirement savings, it's accessing that money early.

The reason? If you take funds out of a traditional IRA or 401(k) before reaching age 59 1/2, you'll be hit with an early withdrawal penalty equal to 10% of the amount you remove from your account. On top of that, you'll pay taxes on your withdrawal, though that would also be the case if you were to remove that money in retirement.

Man in suit holding a hammer aimed toward a piggy bank

IMAGE SOURCE: GETTY IMAGES.

In addition to being penalized for accessing your money early, any amount you remove from your account won't be available to you during your golden years. And that's perhaps an even worse consequence than the aforementioned penalty. Furthermore, it's not just the principal amount you withdraw early that won't be sitting in your account later in life; you'll also lose out on whatever growth that money could've achieved. In other words, taking an early $40,000 withdrawal at age 50 won't just set you back $40,000 in retirement. If that money could've sat in your account another 20 years and generated an average annual 7% return (which is a few points below the stock market's average), it would've grown into $155,000.

And there lies the problem with early withdrawals. Yet year after year, countless Americans access their retirement funds ahead of schedule to address pressing financial needs. Here are the main drivers of this decision, according to GOBankingRates:

Reason for Early Retirement Plan Withdrawal

Percentage of Americans Who Took Early Withdrawals Motivated by That Reason

To pay off debt and/or bills

44%

To pay for medical expenses

22%

To pay for a financial emergency (like job loss)

22%

To purchase a home

9%

To pay for higher education

3%

DATA SOURCE: GOBANKINGRATES.

Now, at first glance, you might argue that all of these are perfectly valid reasons for raiding a retirement plan. In reality, none of the above circumstances should cause you to remove funds from your nest egg before you actually enter retirement.

There's no excuse for tapping your retirement funds

As stated above, the reason for having an IRA or 401(k) in the first place is to ensure that you have enough money to pay your bills in retirement. Remember, your Social Security benefits will help cover your living costs once you retire, but they won't take the place of independent savings. Therefore, you need reserves of your own if you want to maintain a reasonably comfortable lifestyle when you're older. And if you remove funds from your retirement plan along the way, that money won't be there for you when you need it the most.

Furthermore, tapping a retirement plan to pay off debt is a downright irresponsible way to address an existing financial problem. If you're already in debt, make changes to your budget to free up cash to pay down your various obligations. Cut back on luxuries, trim your housing costs by downsizing, and skip vacations until you're debt-free. Or, get a side hustle to earn extra money for paying your debt or covering your bills when they get out of hand. But don't use money earmarked for retirement to make up for your financial sloppiness, because if you do, you'll only be making matters worse.

Additionally, while it's understandable that you might choose to raid your IRA or 401(k) to cover unplanned medical bills -- an expense even the most responsible among us often can't avoid -- the money to cover such bills should really come from your emergency fund instead. The same goes for those who withdraw from retirement savings to cover periods of job loss or unexpected home or car repairs. The purpose of an emergency fund is to cover near-term expenses that arise unexpectedly, so if you've previously tapped your retirement fund because you had no emergency savings, use this as your wakeup call to start building that safety net.

As is the case with paying off debt, you can cut back on expenses or get a side gig to drum up the cash needed to accumulate some savings. That way, you'll have funds to access the next time an emergency arises, and you won't have to fall back on your IRA or 401(k).

Finally, while you're allowed to take penalty-free early withdrawals from an IRA to purchase a first-time home or pay for higher education, you're better off borrowing money to cover those expenses than using money intended for retirement. You can always add to your mortgage or take on a little more student debt, and then pay it off over time. But given today's rates (assuming you're eligible for federal student loans, not private ones), you stand to make more money investing your retirement savings in the stock market than what you'll save on mortgage or student loan interest.

The last thing you want is to end up cash-strapped in retirement. So don't let that happen. Leave your 401(k) or IRA alone during your working years, and find other ways to deal with expenses that pop up along the way. You'll be thankful you did once you kick off your golden years and realize you have that much more income at your disposal.

The Motley Fool has a disclosure policy.