Take a moment and make a list of all the expenses you'll have in retirement. It's not easy, is it? There are a lot of them, and they're not always easy to predict. Most people remember the basics, like food, housing, and transportation. But far too many people are forgetting about the three expenses listed below.

1. Taxes

Most retirees will still have to pay taxes, unless they've stashed all their savings in Roth retirement accounts. You pay taxes on your contributions to these accounts, so your withdrawals in retirement are tax-free. But tax-deferred retirement account contributions reduce your taxable income for that year, so you have to pay taxes on your withdrawals.

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How much you'll owe depends on how much you're withdrawing from your tax-deferred accounts and earning from a job, if you're still working. It isn't always easy to predict this, but you can use the current tax brackets to help you come up with an estimate. Figure out which tax bracket you believe you'll fall into based on your estimated annual retirement spending. Make sure you're saving enough money in your retirement account to cover your expenses as well as your taxes.

Once you reach retirement, keep an eye on where you're at within your tax bracket. If you're nearing the top of the bracket, consider withdrawing funds from your Roth accounts for the remainder of the year to avoid jumping up to the next bracket and owing a larger percentage of your savings to the government.

2. Healthcare

It's no secret that healthcare is expensive and that people usually spend more on healthcare as they age. But many people overlook where those costs come from. Medicare helps you cover some of them, but it also brings costs of its own. You have premiums, deductibles, and copays, just as you would with regular insurance. Make sure you're budgeting for these when you save for retirement. 

Then, there are the things that Medicare doesn't cover, like dental and vision care and hearing aids. There are a few ways you can handle this. You could purchase a Medicare supplement plan to cover some of these things, but this will bring an additional premium, deductible, and copay. You could also choose a Medicare Advantage plan, which effectively replaces your Original Medicare with a plan that covers all of the same things, plus some extras. Or you could look into adding a dental or vision discount program.

For long-term care, consider a long-term care insurance plan, though you should know that these can be expensive. You could also just set aside money for long-term care in your retirement account or health savings account (HSA) if you can afford to do so. 

3. Emergency expenses

Perhaps the most difficult thing to plan for is emergencies in retirement. You don't know when they'll arise, what they'll be, or how much they'll cost. The only way to be truly safe is to build a cushion into your retirement savings

Conventional wisdom tells workers to set aside three to six months of living expenses in an emergency fund to help with unplanned costs. But in retirement, you'll probably want a little more than this. Consider setting aside at least a year's worth of living expenses to help you cover emergency costs.

Keep in mind that not all one-time expenses are emergencies. You might be able to tell that your roof is going to need replacing in retirement. That's something you can plan for outside of your emergency savings. It's a different situation when a roof caves in during a storm, necessitating an unexpected homeowners insurance claim.

Make note of all foreseeable expenses and add these into your retirement budget. This will enable you to reserve your emergency savings for actual emergencies.

This is far from an exhaustive list of all the expenses you might run up against in retirement, but it should get you thinking about some of the costs you should be anticipating. Review your retirement plan to make sure you're as prepared as you can be for all of these expenses. If you're not, make some adjustments now so you're not left scrambling in retirement.