Up to 85 cents of every Social Security dollar you receive could be taxable — yet the IRS reports millions of retirees skip the worksheet entirely and either overpay or face surprise bills in April. I’m Sloane Avery Wren, and on , I sat down with my own SSA-1099 showing $5,980 in net benefits and realized I had no idea what I actually owed. What followed changed how I look at every deposit date on my calendar.
The IRS Social Security taxability worksheet inside Publication 915 (2025) determines whether 0%, 50%, or 85% of your benefit is taxable. Your combined income — not your benefit alone — triggers each tier. Running the numbers before filing can save hundreds of dollars in unnecessary withholding or penalty interest.
Taxable if combined income stays below $25,000 (single) or $32,000 (joint)
Maximum taxable tier for income between $25,000–$34,000 (single filers)
Ceiling tier — triggered above $34,000 single / $44,000 joint combined income
Example net benefit from IRS Publication 915 — used to demonstrate Worksheet 1 steps
Why My SSA-1099 Box 5 Number Blindsided Me This Filing Season
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My SSA-1099 arrived in January showing $5,980 in box 5. That is my net Social Security benefit for the filing year. I thought I understood what that meant. I did not.
The IRS uses the figure in box 5 as the starting point for Worksheet 1 inside Publication 915, which walks you through calculating exactly how much of that amount is taxable. Box 5 is not your gross benefit. It is gross minus any Medicare premiums withheld. That distinction matters because it lowers your starting number — sometimes meaningfully.
In my case, I also receive a small pension — $14,400 per year, or $1,200 a month, roughly what a tank of gas and groceries costs combined in most midsize cities. That pension income gets added to my adjusted gross income and half of my Social Security benefit to create something called combined income. That single number is what actually determines my tax tier.
Walking Through the IRS Worksheet Step by Step in 2026
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Publication 915 provides a concrete example using $5,980 in net Social Security benefits to demonstrate how Worksheet 1 works. I’ll walk through the same logic using my own numbers so you can follow along with yours.
Write down your net Social Security benefit from SSA-1099 box 5. My example: $5,980.
Half of $5,980 is $2,990. This is not yet your taxable amount — just an input.
Add AGI plus tax-exempt interest plus $2,990. This is your combined income. For me: $17,390.
If combined income is below $25,000 (single), your taxable benefit is $0. Above $34,000: up to 85% is taxable.
My combined income of $17,390 fell below the $25,000 threshold. Zero dollars of my Social Security was federally taxable. I almost overpaid because I assumed the full $5,980 would count. That false assumption would have cost me roughly $660 in unnecessary tax at a 22% effective rate.
The worksheet matters most for people in the $25,000–$44,000 combined income band. At $34,001 combined income for a single filer — just one dollar over the upper threshold — you jump to the 85% tier instantly. There is no gradual slope. That cliff is real and it catches people mid-year when a CD matures or a part-time job kicks in.
| Filing Status | Combined Income Range | % of Benefit Taxable | On $5,980 Benefit | |
|---|---|---|---|---|
| Single | Below $25,000 | 0% | $0 taxable | |
| Single | $25,000 – $34,000 | Up to 50% | Up to $2,990 taxable | |
| Single | Above $34,000 | Above $34,000 | Up to 85% | Up to $5,100 taxable |
| Married Filing Jointly | Below $32,000 | 0% | $0 taxable | |
| Married Filing Jointly | $32,000 – $44,000 | Up to 50% | Up to $3,990 taxable | |
| Married Filing Jointly | Above $44,000 | Up to 85% | Up to $6,800 taxable | |
| Married Filing Separately | Any income | Up to 85% | Almost always 85% |
IRS Publication 915 (2025) — thresholds are not adjusted for inflation and have not changed since 1993.
The IRS Worksheet Line by Line: My 2026 Walkthrough
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I run through this worksheet every January after my SSA SSA-1099 arrives. The official version lives in IRS Publication 915 and in the Form 1040 instructions. Here is every line explained in plain language.
Line 1 — Total Social Security Benefits
Enter the amount from Box 5 of your SSA-1099. This is your gross annual benefit before Medicare premium deductions. My 2026 Box 5 reads $22,800.
Line 2 — Multiply Line 1 by 50%
This is the “provisional income base” component of your benefits. Half of my benefit equals $11,400. The IRS uses only half your benefit in the initial test.
Line 3 — Add All Other Income
Include wages, self-employment, pensions, interest, dividends, and capital gains. Also add any tax-exempt municipal bond interest — yes, even tax-free income counts here per IRS Pub. 915, p. 4. I add $18,600 in pension income.
Line 4 — Combined Income (Provisional Income)
Add Lines 2 and 3. This is your combined income or provisional income. Mine is $30,000. Compare this to the threshold for your filing status.
Lines 5–6 — First Threshold Test (50% Tier)
Line 5: Enter $25,000 (single) or $32,000 (married). Line 6: Subtract Line 5 from Line 4. If zero or negative, stop — none of your benefit is taxable. My result: $5,000.
Lines 7–9 — Second Threshold Test (85% Tier)
Line 7: Enter $34,000 (single) or $44,000 (married). Line 8: Subtract Line 7 from Line 4. Line 9: Multiply Line 8 by 85%. If Line 8 is negative, enter zero. My Line 9 result is $0 because I’m below $34,000.
Lines 10–18 — Final Taxable Amount
The worksheet adds the tier results together, then caps the amount at 85% of total benefits. The lesser of the calculated total or 85% of Line 1 is your taxable Social Security benefit. My final taxable amount: $2,500. That goes on Form 1040, Line 6b.
My Real 2026 Calculation: Exact Numbers
I am filing single for tax year 2026. My monthly Social Security payment after the 2.5% COLA is $1,900. Here is my complete worksheet.
Annual SS Benefit (Box 5)
$22,800
50% of Benefits (Line 2)
$11,400
Pension + Interest (Line 3)
$18,600
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