The formula Social Security uses to determine your tax bill

Social Security uses a specific formula to calculate how much of your SSDI is taxable. The calculation depends on your combined income—which includes your SSDI payments plus other income you received that year, plus half of your SSDI benefits themselves. This combined income figure is what determines whether you owe federal income tax on your benefits.

The IRS sets two income thresholds. If your combined income stays below the first threshold, you owe no tax on your SSDI. If it crosses into the second threshold, up to 85 percent of your benefits can become taxable. Most people fall somewhere between these thresholds, where a smaller portion becomes taxable.

The thresholds have not changed since 1984. For a single filer, the first threshold is $25,000 and the second is $34,000. For married couples filing jointly, the first is $32,000 and the second is $44,000. Married people filing separately face a first threshold of $0, meaning any combined income at all can trigger taxation.

Key Takeaways

  • Combined income—not SSDI alone—determines whether you owe tax, and combined income includes half your SSDI benefits plus all other income.
  • The IRS thresholds are $25,000 (single) and $34,000 (single) for the two tiers; married filing jointly are $32,000 and $44,000.
  • If your combined income is below $25,000 (single) or $32,000 (married filing jointly), you owe no federal tax on SSDI.
  • Between the first and second threshold, up to 50 percent of your benefits become taxable; above the second threshold, up to 85 percent can become taxable.
  • State taxes on SSDI vary by state—some states tax SSDI, others do not, and a few tax it only under certain conditions.

What counts as "combined income" in the calculation

Combined income is not the same as your total income. Social Security adds three things together: your SSDI benefits for the year, all other income you received (wages, self-employment income, interest, dividends, rental income, pensions, and distributions from retirement accounts), and half of your SSDI benefits. That last part is the piece that surprises most people—your benefits count twice in the formula, once in full and once at 50 percent.

Some income does not count toward combined income. Tax-exempt interest (usually from municipal bonds) does not count. Supplemental Security Income (SSI) does not count. Certain veterans' benefits and railroad retirement benefits do not count. But almost everything else does—including money from part-time work, rental property, investment accounts, and retirement account withdrawals.

If you are married and file jointly, you combine your SSDI with your spouse's SSDI, your spouse's other income, and your other income. If your spouse has no SSDI but has wages or a pension, that income still counts toward the combined total that determines whether your SSDI becomes taxable.

How the two-tier system works

Once you know your combined income, you compare it to two thresholds. The calculation happens in two steps, and the second step only applies if you cross the second threshold.

First tier: If your combined income exceeds the first threshold ($25,000 for single filers, $32,000 for married filing jointly), you take the amount over that threshold and multiply it by 50 percent. That result is the amount of SSDI that becomes taxable in the first tier—but it cannot exceed 50 percent of your total SSDI for the year.

Second tier: If your combined income also exceeds the second threshold ($34,000 for single, $44,000 for married filing jointly), you calculate the amount over the second threshold, multiply it by 85 percent, and add it to the first-tier amount. The total taxable SSDI from both tiers cannot exceed 85 percent of your benefits for the year.

The IRS publishes a worksheet each year to walk through these calculations. You can also use the Social Security Administration's online calculator, though it requires you to enter your income figures yourself.

A worked example for a single filer

Suppose you received $18,000 in SSDI for the year and $12,000 in part-time wages. Your combined income is $12,000 (wages) plus $18,000 (SSDI) plus $9,000 (half your SSDI) = $39,000.

Your combined income of $39,000 exceeds both thresholds. First tier: $39,000 minus $25,000 = $14,000 times 50 percent = $7,000 in taxable benefits. Second tier: $39,000 minus $34,000 = $5,000 times 85 percent = $4,250. Total taxable: $7,000 plus $4,250 = $11,250. Since $11,250 is less than 85 percent of your $18,000 SSDI ($15,300), the full $11,250 is taxable.

You would report $11,250 of your $18,000 SSDI as taxable income on your federal return. The remaining $6,750 is not taxable. Whether you actually owe tax depends on your total taxable income and your filing status.

State taxes on SSDI vary widely

Federal tax is only part of the picture. Thirteen states tax SSDI benefits under at least some circumstances: Colorado, Connecticut, Kansas, Minnesota, Missouri, Montana, Nebraska, New Mexico, Rhode Island, Utah, Vermont, and West Virginia. The rules differ in each state.

Some states follow the federal formula exactly. Others use their own thresholds or percentages. A few states tax SSDI only if your income exceeds a certain level, or only if you are above a certain age. Vermont, for example, taxes SSDI the same way the federal government does. Colorado taxes it only if your federal adjusted gross income exceeds $20,000 (single) or $25,000 (married filing jointly).

If you live in a state that taxes SSDI, you will need to file a state return even if you do not owe federal tax. Your state tax return will ask for the same combined income information. The amount you owe varies by state and by your specific situation.

What happens if your income changes during the year

The tax calculation is based on your actual income for the full calendar year. If you received SSDI for only part of the year—because you started receiving it mid-year or your case ended—you count only the benefits you actually received in that year.

If your income changes significantly from year to year, your tax situation can change too. A year when you have no other income might result in no tax on your SSDI. A year when you return to part-time work or receive a large distribution from a retirement account could push you into a higher tax bracket. This is why some people find they owe tax one year but not the next.

If you expect your income to be high in a given year, you can ask Social Security to withhold federal income tax directly from your SSDI payments. You do this by completing Form W-4V and sending it to your local Social Security office. Withholding does not change what you owe—it just spreads the payment across the year instead of requiring a lump sum at tax time.

How to report SSDI on your tax return

Social Security sends you a Form SSA-1099 each January showing the total SSDI you received the previous year. You use this form to fill out your federal tax return. The form shows the gross amount; it does not calculate how much is taxable for you.

You report your SSDI on IRS Form 1040 or Form 1040-SR (for people 65 and older). You enter the gross SSDI amount on one line, then use the IRS worksheet to calculate the taxable portion and enter that on another line. If you use tax software, the program will walk you through the calculation.

If you also receive other income—wages, interest, dividends, retirement distributions—you report those on their own lines. The software or the IRS worksheet combines everything to determine your total taxable income and whether you owe tax.

Frequently Asked Questions

Do I have to file a tax return if I only receive SSDI?

Not necessarily. If your SSDI is your only income and it falls below the filing threshold for your age and filing status, you do not have to file. However, if you had taxes withheld from your SSDI, filing a return may get you a refund. The IRS filing thresholds are separate from the SSDI tax thresholds.

What if I have a spouse who does not receive SSDI?

If you file jointly, your spouse's income counts toward your combined income, which can make your SSDI taxable even if your spouse receives no benefits. If your spouse has significant income, you might owe tax on your SSDI even though you would not if you filed separately—though filing separately usually results in more tax overall.

Can I reduce my taxable SSDI by lowering my other income?

Yes, in some cases. If you are close to a threshold, reducing other income—by delaying a retirement account withdrawal, for example—can lower your combined income and reduce or eliminate tax on your SSDI. However, this strategy only works if you have control over when you receive the income.

Does the calculation change if I am over 65?

The SSDI tax calculation itself does not change at 65. However, the standard deduction increases at 65, which can affect whether you owe tax overall. You may also become subject to different filing requirements depending on your total income and filing status.

What if I disagree with the amount shown on my SSA-1099?

Contact Social Security directly to verify the amount. If you received SSDI for only part of the year, or if you had a work incentive that reduced your payment, the form should reflect that. Social Security can issue a corrected form if there is an error.