Saving enough money for retirement is challenging, even if you have a clearly defined plan. What's disturbing is that most people don't even have that much going for them. This causes many to underestimate certain retirement costs and overlook others altogether. Here are five commonly ignored costs that could take a sizable chunk out of your retirement savings if you're not prepared for them.

1. Healthcare

Healthcare is a tricky thing to plan for in retirement because there's no way of knowing how your health will be as you age. Even if you do everything you can to stay healthy, an accident could still leave you seriously injured and unable to care for yourself. Medicare will cover some of your expenses, but you'll still have deductibles, premiums, and copays, and there are some services, like hearing aids, that it doesn't cover at all. 

Mature woman on laptop looking worried

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Estimates for retirement healthcare costs range from $285,000 to over $363,000 for a 65-year-old couple retiring in 2019. These figures represent out-of-pocket costs and do not include the portion that Medicare covers for you. If you're a long way off from retirement, you can expect the medical inflation rate to drive up these costs even more. Add these expenses into your retirement plan if you forgot or underestimated them the first time around. You can use the above figures as a starting point and then adjust them accordingly based on your lifestyle and family health history.

2. Fees

Every retirement account charges fees to cover recordkeeping, account rollovers, and other services. The investments you choose will have fees also. Mutual funds, for example, have expense ratios, which are annual fees charged as a percentage of your assets that all shareholders must pay. Over time, these costs can eat into your profits, forcing you to work even longer to save enough.

You don't want to pay more than 1% of your assets in fees annually. This is $10,000 on a $1 million portfolio. Check your plan summary or the prospectus for your investments to figure out how much you're paying in fees if you're unsure. Typically IRAs are more affordable than 401(k)s, and larger companies offer more affordable 401(k)s than smaller companies because they have more employees to divide the administrative costs, but this may not always be the case.

If your 401(k) charges high fees, talk to your employer about adding lower-cost investment options, like index funds. These are mutual funds that passively track a market index. You could also move your money to an IRA, but this may not make sense if your employer matches some of your contributions. As long as the matched funds are enough to cover what you're losing in fees, you're better off sticking with your 401(k).

3. Debt

It's best to enter retirement debt-free if you can. Even if you think you'll be able to comfortably afford your mortgage or car payment or your credit card debt in retirement, an unexpected emergency could force you to divert some of these funds toward something else. Then, if you fall behind on your bills, you could lose your home or vehicle or end up hounded by debt collectors.

Make debt repayment a priority now so you don't have to worry about it in retirement. Limit your discretionary purchases, work overtime, or seek out side jobs to boost your income and put all your extra cash toward your debt. If you have a large mortgage, consider downsizing to a more affordable place to reduce your monthly payments instead. For credit card debt, consider transferring your balance to a card with a 0% introductory APR or taking out a personal loan to cover the amount so you can have a predictable monthly payment. Getting out from under this debt now can also free up more cash you can put toward your retirement savings so you can retire more comfortably.

4. Taxes

You will still owe taxes in retirement unless all your savings are in Roth accounts. How much you'll owe depends on how the tax brackets fall that year and how much you withdraw from your retirement accounts. There's no way to predict this with accuracy, but you can estimate it using the current tax brackets and your estimated annual retirement expenses.

Use this as your baseline, but remember, you'll owe taxes only on the amount you withdraw from tax-deferred savings. So if, for example, you had half your savings in a tax-deferred account and half in a Roth account and you intended to withdraw 50% of your retirement expenses from the Roth account and 50% from the tax-deferred account one year, you'd owe taxes on only half of your annual living expenses. You may have to beef up your retirement savings plan if you didn't account for taxes when you first created it; you want to ensure you have enough money to pay your tax bills when the time comes.

5. Your kids

Many parents today help their children pay for their college education so they don't have to take out as much in student loans. This is noble, but you shouldn't let it inhibit your retirement savings. Putting yourself first can feel selfish, but it's actually better for your children in the long run. They may have to take out some student loans to cover their education, but if you can't save up enough money for retirement because you were too busy saving for their college, you'll run out of money and your children will have to care for you. This can cost them far more than student loans would cost, especially if you end up needing a lot of medical care in your old age. 

Some parents or grandparents may also take out loans in their own names to cover their child's education. But if you carry this debt into retirement, you may have to spend less on the activities you enjoy, and you run the risk of jeopardizing your financial security if a major expense arises and you're unable to keep up with your debt payments. Always focus on your own financial goals first, and if you have extra money left over, you can put it toward helping your children.

Your retirement savings are what's going to keep a roof over your head and food on your table when you're no longer working. It needs to be a high priority, and you can't afford to let the five expenses above eat into those precious savings. Redo your retirement plan if you haven't accounted for any of these things, and make a plan for how you'll handle any debt you have before you reach retirement so it doesn't become a burden to you.