How combined income affects SSDI taxes
The Internal Revenue Service (IRS) uses a calculation often called combined or provisional income to determine whether Social Security benefits are taxable. The IRS provides a simple test that can provide a quick way to determine if your benefits are taxable. The test adds up:
- Half of your Social Security benefits
- Tax-exempt interest
- All other income
Then you would compare the total to your Base amount of income as shown below.
When SSDI benefits become taxable
How much of your SSDI may be taxable depends on your combined income:
- Single filers: Up to 50% may be taxable above $25,000, and up to 85% may be taxable above $34,000.
- Married filing jointly: Up to 50% may be taxable above $32,000, and up to 85% may be taxable above $44,000.
This doesn’t mean the IRS taxes your benefits at an 85% tax rate. It means up to 85% of the benefit may be included in your taxable income.
| Filing status | Combined income base amount (up to 50% taxable) | Higher threshold (up to 85% taxable) |
|---|---|---|
| Single, head of household, or qualifying surviving spouse | $25,000 | $34,000 |
| Married filing jointly | $32,000 | $44,000 |
| Married filing separately (lived apart all year) | $25,000 | $34,000 |
| Married filing separately (lived together at any point) | - | $0 |
Source: Internal Revenue Service (1, 2)
For example, if your only income is $18,000 in SSDI, half is $9,000. That’s below the $25,000 base amount for a single filer, so none of those benefits would generally be taxable.
SSDI back pay and lump-sum payments
If you receive SSDI back pay covering an earlier year, you generally report the taxable portion in the year you receive the payment. You don’t amend prior-year returns simply to move the benefits into those years. There is a different calculation to determine additional taxable benefits on the lump-sum payment, which utilizes your AGI.
The lump-sum election in IRS Publication 915, which covers the tax treatment of Social Security and equivalent railroad retirement benefits, may let you use your income from the earlier years to calculate how much of the back payment is taxable. This can sometimes reduce the taxable amount without requiring amended returns.
Reasons to file even if you aren’t required to
Filing may still make sense if:
- You had federal income tax withheld from a job or other income and are due a refund.
- You qualify for a refundable tax credit based on other income or circumstances.
- You had other income that creates a filing requirement.
Keep in mind that SSDI itself isn’t earned income for the Earned Income Tax Credit (EITC). You generally need qualifying earned income from work to claim the credit.
If your benefits are taxable, you can also request federal income tax withholding from future Social Security payments using Form W-4V.
