Why Up to 85% of Your Social Security Can Be Taxed, and How to Keep More of It

Picture a married couple, both retired, collecting $40,000 a year in combined Social Security. They also take $30,000 from a traditional IRA. When they run the IRS worksheet, they find that a meaningful slice of their benefits is now taxable. Add a $10,000 IRA withdrawal for a new roof, and their taxable income rises by more than $10,000. That second effect is the part most retirees never see coming.

Federal tax on Social Security benefits is not a flat percentage of your check. It depends on a separate income figure, and the share of benefits that can be taxed climbs from zero to 50% to a maximum of 85% as that figure rises. No one pays 85% of their benefits in tax. Up to 85% of benefits can be included in taxable income, and then ordinary tax rates apply to that amount.

The number that decides everything

The tax code compares your income with what it calls a base amount, and many planners call the income side of that test provisional or combined income. Under Section 86 of the tax code, you add your modified adjusted gross income to one half of your Social Security benefits. Modified adjusted gross income here includes items such as tax-exempt interest, which surprises people who hold municipal bonds precisely to avoid tax.

That total is then compared with fixed dollar thresholds. IRS Publication 915 sets them out. For single filers, heads of household, qualifying surviving spouses, and married people filing separately who lived apart all year, the first threshold is $25,000. For married couples filing jointly, it is $32,000.

Above a second threshold, up to 85% of benefits can become taxable. That threshold is $34,000 for single filers and $44,000 for joint filers. Married people who file separately and lived with their spouse at any time during the year face the harshest rule: up to 85% of benefits can be taxable without the usual base amount cushion.

Why the thresholds keep catching more people

These dollar amounts are written into the statute and are not adjusted for inflation. Wages, IRA balances, and benefits themselves have grown for decades, while the trigger points have stayed put. Each year, more middle-income retirees cross them simply because their other income and benefits drift upward.

This is also why a cost of living raise can nudge a household's taxes, a point covered in our look at the 2027 adjustment. The focus here is different: what you control on the other side of the formula, namely your other income.

The three zones in plain terms

Below the first threshold, none of your benefits are taxable. Between the two thresholds, the taxable portion grows by 50 cents for each dollar of income above the first threshold, up to a cap. Above the second threshold, each additional dollar of income adds 85 cents of taxable benefits, again until 85% of total benefits are taxable.

Once you reach that 85% ceiling, the special effect ends. More income is simply taxed at your normal bracket. That detail matters for planning, because the costly zone is the middle, not the top.

A single filer, line by line

Numbers make the formula easier to trust, so here is a simplified example for a single retiree. She receives $24,000 a year in Social Security and has $28,000 of other income, mostly IRA withdrawals and some interest. One half of her benefits is $12,000, so her provisional income is $40,000.

That is $15,000 above the $25,000 first threshold and $6,000 above the $34,000 second threshold. Under the statutory formula, the taxable portion is the smaller of two figures. The first is 85% of the $6,000 excess, or $5,100, plus $4,500. That second piece is capped at half of the $9,000 gap between the two single thresholds once income is this high. That gives $5,100 plus $4,500, or $9,600. The second figure is 85% of her total benefits, which is $20,400. The smaller amount, $9,600, is included in her taxable income.

Now suppose she withdraws another $2,000 from her IRA. Provisional income rises to $42,000, the excess above $34,000 becomes $8,000, and the taxable portion becomes $6,800 plus $4,500, or $11,300. Her $2,000 withdrawal increased taxable income by $3,700. That is the torpedo in miniature.

Publication 915 has worksheets that perform these steps, and tax software runs them automatically. Running a quick projection with a draft withdrawal amount before you request the money is often more useful than discovering the result in April.

The tax torpedo, worked as an example

Here is why the couple's roof money hurt. Suppose they are in the 85% phase-in range and in the 12% federal bracket. Each extra $1,000 drawn from the IRA adds $1,000 of ordinary income plus $850 of newly taxable benefits, so $1,850 of taxable income in total.

At 12%, that is about $222 of federal tax on a $1,000 withdrawal, an effective marginal rate of roughly 22.2%. If the same household were in the 22% bracket while still in the phase-in range, the effective rate would be about 40.7%. These figures are illustrative and assume no other credits or phaseouts are affected, but the pattern holds.

Planners call this the tax torpedo. It is not a separate tax. It is the interaction between ordinary brackets and the benefit inclusion formula, and it explains why two retirees with similar incomes can face very different marginal rates.

Lever one: Roth conversions before benefits start

The cleanest way to shrink future provisional income is to reduce how much taxable IRA money you will need later. Converting part of a traditional IRA to a Roth IRA creates taxable income in the year of conversion, but qualified Roth withdrawals later are not included in adjusted gross income.

The timing is what makes this work. Many people have a window between retirement and the start of Social Security, or before required minimum distributions begin at age 73, when taxable income is unusually low. Converting during those years can fill lower brackets on purpose.

The catch is that a conversion done after benefits begin is itself income for the formula. A large conversion in a year you already receive Social Security can push more benefits into tax that same year. Conversions also raise adjusted gross income for other purposes, such as Medicare premium surcharges, so the size of each year's conversion deserves a careful estimate.

Lever two: the order you draw from accounts

Retirees often hold three kinds of money: taxable brokerage accounts, tax-deferred accounts like traditional IRAs and 401(k)s, and Roth accounts. Each affects provisional income differently.

Withdrawals from a traditional IRA are fully counted. Selling investments in a taxable account counts only the realized gain, not the full sale proceeds. Qualified Roth withdrawals do not count at all. Spending cash from a savings account does not create income either, though the interest it earned along the way does.

A household near a threshold can sometimes stay below it by blending sources. For example, taking part of a year's spending from a brokerage account with high cost basis, or from Roth money, can keep IRA withdrawals in a lower zone. There is no universal order. The right blend changes year to year and depends on balances, brackets, and how long each pool needs to last.

Lever three: qualified charitable distributions

If you give to charity and are at least age 70 and a half, a qualified charitable distribution can be one of the most efficient moves available. Publication 590-B describes a QCD as a distribution made directly by the IRA trustee to an eligible charity. The amount is excluded from income and can count toward a required minimum distribution.

Because a QCD never enters adjusted gross income, it does not raise provisional income. Writing a check from your bank account and then itemizing can be far less effective, especially for retirees who take the standard deduction anyway. IRS Notice 2025-67 sets the 2026 annual QCD exclusion limit at $111,000 per person, up from $108,000 for 2025.

The mechanics matter. The money must go straight from the IRA to the charity, and you need the same acknowledgment you would need for a deductible gift. Confirm with your IRA custodian and the charity that the recipient qualifies before the transfer is made.

Lever four: timing lumpy income

Many retirees have one-time income events: selling a rental property, exercising old stock options, cashing out an annuity, or a large capital gain. Bunching that income into a single year can push benefits to the 85% ceiling for that year while leaving other years untouched. Spreading it across years can sometimes keep more years in a lower zone.

Neither approach is automatically better. If one year of high income gets you past the costly middle zone quickly, concentrating the income may cost less than dribbling it out over several years inside the phase-in range. Run both versions through the worksheet or software before you decide.

Retroactive benefit payments create a special case. If you receive a lump sum covering earlier years, Publication 915 allows a lump-sum election that can figure the taxable portion as if the money had been received in those earlier years. It can reduce tax in the year the lump sum arrives.

The widow's version of the problem

Thresholds also shift when a household's filing status changes. A married couple filing jointly uses the $32,000 and $44,000 figures. After one spouse dies, the survivor generally files as single in later years unless another status applies, and the thresholds drop to $25,000 and $34,000.

Household income often falls by less than that. The survivor can generally receive the larger of the two Social Security benefits, but not both, and inherited IRA balances may still require withdrawals. In this example pattern, a widow with somewhat lower income can find more of her benefits taxable than when both spouses were alive. Couples who plan conversions together while both are living are, in part, planning for the survivor's tax picture.

What to check before filing

Your Form SSA-1099 shows net benefits for the year in box 5, and Publication 915 says to use that box 5 figure in the worksheet. Do not reduce it by Medicare premiums that were deducted from your benefits.

If your benefits will be taxable, consider voluntary federal withholding from your Social Security payments using Form W-4V, or make estimated payments. Underpaying through the year can trigger penalties even when the total tax is small.

State rules differ. States set their own rules for Social Security benefits, and they do not follow the federal formula automatically. Check your state's revenue department rather than assuming federal treatment carries over.

Focus your planning on the middle zone and on the years before benefits and required distributions begin. A few modest choices about conversions, withdrawal order, and charitable giving can keep thousands of dollars of benefits out of tax over a retirement.