You may not particularly enjoy paying taxes as a member of the workforce. But at least you know to expect them.

Retirees, however, are often caught off guard by the idea of paying taxes. And many end up struggling financially because of that.

The last thing you need in retirement is an unwanted tax surprise. So with that in mind, here are a few forms of retirement income you might end up paying taxes on.

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1. Social Security benefits

You might assume your Social Security payments are yours to enjoy free and clear of taxes. And if they're your only source of income, that might end up being true. But many seniors end up in an income bracket where federal taxes on Social Security benefits apply.

To know if you'll face taxes on Social Security, you'll need to estimate your provisional income during retirement. That's figured by taking your modified adjusted gross income and adding in 50% of your annual Social Security benefits. If the total exceeds $25,000 and you're single, or $32,000 and you're married, then expect at least some of your Social Security income to be taxed.

And that's just at the federal level. There are certain states that tax Social Security as well.

2. Traditional retirement plan withdrawals

Paying taxes on retirement plan withdrawals isn't a given. And if you have a Roth IRA or 401(k), those won't be an issue.

But many savers opt to put their money into a traditional IRA or 401(k) plan due to the up-front tax benefits involved. You should know, however, that withdrawals from a traditional IRA or 401(k) will be subject to taxes, so plan for those accordingly.

3. HSA withdrawals for non-medical spending

Many people spend their working years funding a health savings account (HSA) so they have a means of covering their healthcare expenses once they're older. If you withdraw from an HSA during retirement to cover things like medications and doctor visits, you won't be taxed on those distributions.

Once you turn 65, however, you're allowed to take HSA withdrawals for non-medical purposes without being charged a penalty (whereas non-medical withdrawals prior to 65 will be penalized). But in that case, you are looking at taxes on the money you remove.

Of course, many seniors wind up having to reserve their HSA funds for healthcare expenses only, so this may not end up being an issue for you. But if you happen to be blessed with really good health as a senior, or you choose your Medicare coverage wisely, then you may wind up with excess funds in your HSA. And it's important to know what that might mean from a tax perspective.

Know what to expect

Taxes during retirement are something you can learn to manage, the same way you manage to cope with them during your working years. The key, however, is to not be taken by surprise. So it's a good idea to read up on the different forms of retirement income you might be taxed on, and to consult a financial advisor or accountant for advice on how to potentially minimize your IRS burden as a retiree.