Many retirees are surprised to learn that Social Security benefits can be taxed. The rules are confusing because they hinge on a special figure called “combined income” that doesn’t appear on any single tax form. Here’s how it actually works — what gets taxed, when, and how to plan around it.
Are Social Security benefits taxable?
Sometimes. Whether your benefits are taxed and how much depends on your other income. If Social Security is your only source of income, your benefits are usually not taxed at all. But once you have meaningful additional income — from a pension, retirement account withdrawals, part-time work, or investment income — up to 85% of your benefits can become taxable on your federal return.
“Up to 85%” means up to 85% of your benefits are included in your taxable income, not that 85% gets taken in tax. The amount actually owed depends on your tax bracket.
How combined income works
The IRS uses a calculation called combined income (sometimes called “provisional income”) to decide whether your benefits are taxed. The formula:
- Your adjusted gross income (AGI), excluding Social Security
- Plus any tax-exempt interest (such as municipal bond interest)
- Plus half of your annual Social Security benefits
That total is your combined income. The thresholds determine how much of your benefits are taxable:
If you file as single, head of household, or qualifying surviving spouse
- Combined income under $25,000 — benefits are not taxed
- Combined income $25,000 to $34,000 — up to 50% of benefits are taxable
- Combined income over $34,000 — up to 85% of benefits are taxable
If you file as married filing jointly
- Combined income under $32,000 — benefits are not taxed
- Combined income $32,000 to $44,000 — up to 50% of benefits are taxable
- Combined income over $44,000 — up to 85% of benefits are taxable
If you file married filing separately
If you lived with your spouse at any point during the year, up to 85% of your benefits are taxable regardless of income. This rule essentially eliminates the income thresholds for most separate filers.
Why these thresholds catch people off guard
The thresholds were set in 1983 (50%) and 1993 (85%) and have never been adjusted for inflation. A retiree with $25,000 in income in 1983 dollars had real purchasing power; today, that same nominal threshold catches almost everyone with modest retirement savings. Each year, more retirees cross into the taxable zone simply because cost-of-living increases push their benefits higher while the thresholds stay frozen.
A simple example
A married couple files jointly. Their income for the year:
- $30,000 from a pension
- $10,000 in IRA withdrawals
- $2,000 in dividends
- $36,000 in Social Security benefits
Their combined income calculation:
- AGI excluding Social Security: $42,000
- Plus half of Social Security ($18,000): $60,000
- Combined income: $60,000
Because $60,000 is over $44,000 (the joint filing 85% threshold), up to 85% of their $36,000 in benefits — about $30,600 — gets added to their taxable income. The actual tax owed depends on their bracket. In the 12% bracket, that’s roughly $3,672 in federal tax on the Social Security portion alone.
State taxes on Social Security
Most states do not tax Social Security benefits. As of 2026, the small number of states that still tax some Social Security income include Colorado, Connecticut, Minnesota, Montana, New Mexico, Rhode Island, Utah, Vermont, and West Virginia — though many of these have age-based or income-based exemptions that exclude lower- and middle-income retirees. Several states have phased out their Social Security tax in recent years, so the list shrinks each year.
Check your state’s current rules. If you’re considering relocating in retirement, state taxation of Social Security is one factor — but rarely the deciding one, since other taxes (property, sales, income) often matter more.
How to plan around Social Security taxation
1. Manage your withdrawal order
The order in which you tap retirement accounts affects how much of your Social Security gets taxed. Withdrawing from a traditional IRA or 401(k) raises your AGI — which raises your combined income — which can push more of your benefits into the taxable zone. Roth withdrawals don’t count toward AGI, so they don’t affect Social Security taxation.
2. Consider Roth conversions before claiming
Converting traditional IRA money to a Roth IRA in years before you start Social Security can reduce future required minimum distributions (RMDs) — which are the main thing that pushes retirees over the 85% threshold later. The trade-off: conversions are taxable in the year you do them, so the strategy works best in low-income years before benefits start.
3. Watch your tax-exempt interest
Municipal bond interest is tax-free at the federal level, but it is counted in the combined income formula. A retiree heavily invested in munis can still trigger Social Security taxation even with low taxable income.
4. Be aware of one-time income spikes
A large capital gain, a Roth conversion, or an unusual withdrawal in a single year can push you across the 85% threshold for that year. If you have flexibility in when to recognize income, spreading it across years sometimes reduces the total tax bill.
5. Have taxes withheld from benefits
If you owe tax on your benefits, you can ask the Social Security Administration to withhold federal income tax directly — at 7%, 10%, 12%, or 22%. File Form W-4V with your local Social Security office. This avoids a surprise bill at tax time and is often simpler than making quarterly estimated payments.
How taxes connect to Medicare premiums
Higher income in retirement also affects Medicare. Once your modified adjusted gross income crosses certain thresholds, you pay IRMAA — an income-related surcharge on your Part B and Part D premiums. The thresholds are based on tax returns from two years prior, so a Roth conversion or large withdrawal today can raise your Medicare premiums two years from now. Coordinated tax planning addresses both at once.
Common mistakes to avoid
- Assuming Social Security is tax-free. For most retirees with any meaningful additional income, it isn’t.
- Not setting aside money for taxes. The Social Security Administration doesn’t withhold automatically. If you owe tax, you owe it — and a year of un-withheld benefits can produce a five-figure tax bill.
- Forgetting that municipal interest counts. Tax-exempt at the federal level doesn’t mean it’s ignored for Social Security purposes.
- Triggering the 85% threshold with a one-time event. A property sale, IRA-to-Roth conversion, or large RMD can do this without warning.
- Overlooking the IRMAA connection. Higher income today can mean higher Medicare premiums two years out.
The bottom line
Up to 85% of your Social Security benefits can be added to your taxable income, depending on your other income. The thresholds are low and frozen, so most retirees with modest savings end up owing some tax on benefits. The good news: with planning — especially around the order of withdrawals, Roth conversions, and IRMAA timing — you can manage how much. The bad news: ignoring the issue produces a surprise tax bill that catches new retirees off guard every year.
Further Reading
- Taxes in Retirement
- Social Security and Taxes (Tax Hub)
- How Social Security Retirement Benefits Are Calculated
- When to Claim Social Security
- Working While Collecting Social Security
This article is for general educational purposes only and does not constitute tax or financial advice. Tax rules change and individual situations vary — consult a tax professional or the IRS for guidance specific to your circumstances.
