When planning for retirement, most people only factor in the day-to-day costs when calculating how much they'll need to spend their golden years comfortably. As you budget your retirement to gauge your monthly costs, you're probably focused the most on mortgage or rent payments, credit card bills, groceries, and other basic monthly costs.

But where does healthcare fit into that budget? Some retirees may think they don't need to plan for healthcare costs because once they're eligible for Medicare, they assume their medical needs will be covered. However, Medicare isn't completely free, and there are still costs involved.

In fact, the average 65-year-old couple retiring today can expect to pay roughly $275,000 in healthcare costs during retirement, according to a recent Fidelity study. That number includes Medicare premiums, copayments, and deductibles, as well as prescription drug expenses that Medicare doesn't cover.

There are also several other services that Medicare doesn't cover, including hearing aids and routine hearing tests, routine eye care, routine dental work, and custodial care (which includes nursing home care). As your body ages, the realistic (although not pleasant) assumption is that you'll be taking more frequent trips to the doctor, and these costs can add up quickly.

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Don't happen to have an extra $275,000 lying around to cover these healthcare expenses? You're not alone. The average amount families age 56 to 61 have saved for retirement is just $163,000 -- and according to Fidelity's estimate, that's nowhere near enough to cover healthcare, let alone all your retirement expenses.

Fortunately, though, there are a few things you can do to save more money and cut down on healthcare costs during retirement:

1. Enroll in a health savings account

Health savings accounts, or HSAs, allow you to contribute money pre-tax, let it grow, then withdraw tax-free as long as you put it toward qualifying medical expenses. The primary goal of an HSA is to help combat high deductibles that make healthcare unaffordable to many people, so they're a great idea if you're facing high Medicare deductibles during retirement.

For 2017, the maximum annual contribution limit is $3,400 for individuals or $6,750 for families (add $1,000 to those numbers if you're age 55 or older). And another benefit of HSAs is that because you're contributing pre-tax dollars, that can lower your taxable income by however much you contribute per year, saving you money.

If you're strategic about investing in your HSA, you can save even more money. By enrolling in an account early in life, you can take advantage of compound interest and watch your savings grow. Then you can choose a high-deductible insurance plan to get the benefit of lower monthly premiums, using your HSA funds to cover those high deductibles when necessary.

2. See if your employer offers retiree healthcare coverage

Because Medicare doesn't cover everything, some retirees choose to enroll in supplemental insurance to cover routine exams and other health services they'd otherwise be paying for out of pocket. Some employers let you stay on the company healthcare plan even after you retire, so if you're concerned about healthcare costs, check with your employer to see if this is an option.

Employers aren't required to offer coverage to retirees, and if they do, there are often rules accompanying it. The coverage may or may not cover your spouse, for instance, and the employer has the ability to change premiums or even cancel coverage. Also, if you're eligible for Medicare and choose not to enroll, your employer may deny you retiree coverage.

Talk to your healthcare plan provider to see if retiree insurance is offered at your company, and if so, how much it costs and what it covers. If you're expecting high healthcare costs -- even with Medicare -- retiree insurance could save you a lot of money.

3. Make health and wellness a priority leading up to retirement

This one may seem obvious, but taking care of your health before you retire can save you money after you retire.

Smokers, for example, can expect to pay roughly 15% to 20% more in premiums than non-smokers, plus there are potential health issues that can cost thousands of dollars in medical expenses. Similarly, those who are obese pay about 56% more in healthcare expenses than those at a healthy weight.

Although taking care of your health won't eliminate healthcare costs, it can help reduce them by lowering your risk for certain illnesses or diseases.

There are a lot of factors to consider when planning how much money you'll need during retirement, and healthcare is a major one. Even with Medicare, you can still expect to pay thousands (or hundreds of thousands) of dollars out of pocket, so by creating a plan early and preparing for these costs, you'll ensure you're not caught by surprise when the doctor's bill arrives.