Retirement income comes from a lot of different places — pensions, investment accounts, Social Security, property, savings — and the IRS treats each of them differently. Understanding those distinctions matters, because the tax treatment of your income streams affects not just your annual tax bill but also how much of your Social Security benefit gets taxed and potentially your Medicare premium costs.
Fully taxable income
Wages from any form of employment, including part-time or freelance work, are taxed as ordinary income. So are withdrawals from traditional IRAs and 401(k) plans, since those accounts were funded with pre-tax contributions and the tax liability was deferred until withdrawal. This becomes particularly significant once you reach required minimum distributions (RMDs) at age 73, when the IRS requires you to start drawing down a portion of those accounts each year regardless of whether you need the funds.
Interest income from bank accounts, bonds and certificates of deposit is also fully taxable, with the notable exception of municipal bond interest, which is generally exempt from federal tax and sometimes from state and local tax too. Pensions are almost always fully taxable unless you made after-tax contributions to the plan during your working years.
Partially taxable: Social Security
Social Security benefits occupy their own category. Up to 85% of your benefits can be subject to federal income tax depending on your total income. If your combined income — defined as adjusted gross income, plus tax-exempt interest income, plus half of your annual Social Security benefit — falls below $25,000 (or $32,000 for married couples filing jointly), your benefits are not federally taxed. Between $25,000 and $34,000 ($32,000 to $44,000 for married couples), up to 50% of your benefit becomes taxable. Above $34,000 ($44,000 for couples), up to 85% is taxable.
Tax-free income sources
Roth IRAs and Roth 401(k) plans are funded with after-tax contributions, meaning qualified withdrawals are completely tax-free. Roth accounts also do not count toward the combined income calculation that determines Social Security taxation, and they are not subject to RMDs — two significant advantages in retirement planning. Withdrawals from health savings accounts (HSAs) used for qualified medical expenses are also tax-free, as are inherited Roth IRA distributions and life insurance payouts received as a beneficiary.
Planning around these distinctions
The way your income is structured in retirement directly affects how much tax you pay. One widely used strategy is a partial Roth conversion before retiring — moving money from a traditional IRA to a Roth IRA in years when your income is lower. You pay tax on the converted amount at the time of conversion, but future withdrawals come out tax-free and don’t add to the combined income figure used to calculate Social Security taxation.
Mapping out all your income sources by their tax treatment is a useful starting point. Knowing which streams are fully taxable, which are partially taxable, and which are exempt gives you a clearer picture of your effective tax burden in retirement — and more scope to adjust it in advance.