Social Security could end up being an important income stream for you in retirement. And you might assume that once those benefits start rolling in, they'll be yours to keep in full.

But one thing many retirees fail to realize is that Social Security benefits can be subject to federal taxes. In fact, you could end up paying taxes on up to 85% of your benefits, depending on what your retirement income looks like.

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Understanding how taxes on benefits work could help you make strategic savings decisions that help you avoid losing a chunk of your hard-earned Social Security checks.

It's all about provisional income

It's not a given that your Social Security benefits will be taxed. Whether that happens hinges on your provisional income, which is the total of your adjusted gross income (AGI), tax-exempt interest income you collect, and 50% of your annual Social Security benefits.

If you're single with a provisional income between $25,000 and $34,000, up to 50% of your Social Security benefits may be taxable. Once your provisional income exceeds $34,000, up to 85% of your benefits may be subject to federal income tax.

For married couples filing jointly, the thresholds are higher. Provisional income between $32,000 and $44,000 can make up to 50% of benefits taxable, while income above $44,000 could make up to 85% of benefits taxable.

Unfortunately, these thresholds are not adjusted for inflation. So if your income rises from year to year, you may find that you have to pay taxes on your Social Security checks -- even if you didn't start out having to.

A Roth retirement plan could come to your rescue

If you don't like the idea of having to pay taxes on your Social Security benefits, one potential solution is to save for retirement in a Roth IRA or 401(k). Roth account withdrawals don't count toward your AGI, since they're tax-free. That means you may be able to keep your provisional income low enough to avoid taxes on your Social Security benefits.

Of course, having money in a Roth account doesn't guarantee that your Social Security won't be taxed. But it's one way to potentially lower your risk.

And if you can't get out of paying taxes on Social Security, it's not necessarily going to wreck your retirement finances. But it is important to know that those taxes exist and prepare for them if you're on the hook.