How Much of Social Security Is Taxable With Rental and K-1 Income

The rule, with the exact numbers

IRC section 86(a) works in two bands. In the first, the taxable part is “the lesser of” half the benefits or half the excess of your test amount over the base amount. In the second, it is 85% of the excess over the adjusted base amount plus the lesser of the first-band amount or half the gap between the two lines, again capped at 85% of the benefits. The test amount is modified adjusted gross income plus half the benefits (section 86(b)(1)). Publication 915 says it in plain words: compare your base amount with “one-half of your benefits” plus “all your other income, including tax-exempt interest.”

Source: IRC section 86(a), (c)(1), (c)(2); IRS Publication 915 (2025), “Base amount” and Worksheet 1 lines 9 to 19. The “most the first band can add” column is our arithmetic: half of $9,000 and half of $12,000, the amounts on Worksheet 1 line 11.

These numbers do not move. The Code states them as fixed dollars, with no cost-of-living clause. Rev. Proc. 2025-32 sets the 2026 inflation adjustments in 63 numbered items, from the tax brackets to the standard deduction to the foreign earned income exclusion in section 911, and section 86 is not one of them (our reading of its table of contents). Benefits can rise with cost-of-living adjustments while these thresholds cannot, so over time more of a typical retiree’s income sits above the lines (our reading). The 2025 edition of Publication 915 prints the same $25,000, $32,000, $34,000 and $44,000.

Do it yourself in six lines (our calculator, same as the IRS worksheet)

This is the logic of Publication 915 Worksheet 1 and the Social Security Benefits Worksheet in the Instructions for Form 1040, in the order a person would do it.

1. Benefits (B). The total of box 5 of every Form SSA-1099 and RRB-1099. It goes on Form 1040 line 6a.
2. Other income (O). Add Form 1040 lines 1z, 2b, 3b, 4b, 5b, 7a and 8, then subtract the Schedule 1 adjustments on lines 11 through 20, 23 and 25. Do not subtract the student loan interest deduction, and do not subtract the standard deduction.
3. Tax-exempt interest (T). Form 1040 line 2a. Add foreign earned income you excluded, and the other exclusions Publication 915 lists.
4. Provisional income (P) = O + T + B / 2.
5. If P is at or below the base amount, nothing is taxable. If P is between the base and the adjusted base, the taxable part is half of (P minus the base), but not more than half of B.
6. If P is above the adjusted base, the taxable part is 85% of (P minus the adjusted base) plus the lesser of half of B or the first-band amount ($4,500 single, $6,000 joint), but not more than 85% of B. The result goes on line 6b.

Our script reproduces the IRS’s own filled-in examples: Publication 915 Example 1 (single, $5,980 of benefits, $28,990 of other income) comes out at $2,990, and Example 3 (joint, $10,000 of benefits, $40,500 of other income) at $6,275, both as printed in the publication (our arithmetic).

What counts in provisional income, and what does not

The test reads the return line by line. The table gives the item, whether it counts, and the reason.

Source: IRC sections 86, 199A and 469; IRS Publication 915 (2025) Worksheets A and 1 and its “Exclusions” list; Form 1040 (2025), Schedule 1 and Schedule E; Instructions for Form 1040 (2025); IRS Publications 550 and 590-B (2025). The cash-versus-net and K-1 examples are our arithmetic.

Why a rental net counts and a return of capital does not

Both can arrive as a check, so they look alike. The return treats them differently. A rental produces Schedule E line 26, “Total rental real estate and royalty income or (loss)”, and the form’s own instruction sends that amount to Schedule 1, line 5. Schedule 1 line 10 goes to Form 1040 line 8, and line 8 is one of the lines the worksheet adds. Depreciation lowers the net, so it lowers the test while you own the property; when you sell, the recapture is part of the gain and comes back in (see depreciation recapture).

A return of capital never reaches those lines. Publication 550 says a nondividend distribution “reduces the basis of your stock” and “is not taxed until your basis in the stock is fully recovered”, and that it shows in Form 1099-DIV box 3. That is why many non-traded REIT distributions in the early years cost nothing in Social Security terms. The catch is the same sentence one step on: when basis has been reduced to zero, “report any additional nondividend distribution you receive as a capital gain.” That gain is on line 7a and in the test. The two REIT rows in the scenario table below show the effect on the same $30,000 of cash. See our guide to REIT return of capital and how to read a K-1.

Five different “modified AGI” numbers

The same two words mean five different things in five places. Mixing them is the commonest planning mistake in this area.

Source: IRC sections 86(b)(2), 1411(b) and (d), 469(i)(3)(A) and (E), 151(d)(5)(C); SSA POMS HI 01101.010 (effective December 2, 2025); Schedule 1-A (Form 1040) 2025, Part V.

One consequence is a loop that the Code breaks for you. Taxable Social Security raises your AGI, which counts for Medicare and for the senior deduction, but is left out of the test for the passive-loss allowance. The Social Security test in turn uses an AGI that leaves taxable benefits out of itself. Our IRMAA guide covers the Medicare side in full, our net investment income tax guide the 3.8% tax, and our passive loss guide the allowance.

Where the tax starts, by benefit size

The breakpoints depend on how large your benefit is, because half of it is already in the test. “Other income” below is your AGI before Social Security, with no tax-exempt interest.

Source: our arithmetic from IRC section 86(a) and (c); validated against Publication 915 Examples 1 and 3. Tax-exempt interest of $1 moves each figure down by $1.

Above the last column the taxable amount stops growing. At that point more income no longer makes more benefits taxable, which is why large sales and conversions can look cheaper per dollar than a modest amount of extra income in the middle of the band.

The tax torpedo: the marginal rate inside the band

“Tax torpedo” is a planning nickname, not an IRS term. The mechanism is in the worksheet: in the 85% band, each extra dollar of other income raises the test by $1 and the taxable benefits by $0.85, so you are taxed on $1.85 for each $1 you earn. In the 50% band it is $1.50. The effective rate is your bracket multiplied by 1.85, then by a further 1.06 or 1.12 where the senior deduction is being phased out.

Source: our arithmetic. Brackets are the 2026 rates in Rev. Proc. 2025-32 section 4.01; the 1.85 and 1.50 come from IRC section 86(a); the 1.06 from IRC section 151(d)(5)(C)(iii), a 6% phase-out of a $6,000 deduction, which applies to taxable years beginning before January 1, 2029.

The multiplier only bites where there is tax to multiply. A retiree with large deductions pays 0% on the first slice of income, and the torpedo is invisible there. These two profiles come from our script (everyone 65 or older, the 2026 standard deduction with the additional amount for age, the $6,000 senior deduction per person, all other income ordinary, no state tax). Edges are rounded to the nearest $100.

Source: our arithmetic (our script) on Rev. Proc. 2025-32 sections 4.01, 4.03 and 4.14; IRC sections 86 and 151(d)(5)(C); Schedule 1-A (Form 1040) 2025, Part V lines 31 to 37. The joint standard deduction of $32,200 plus $1,650 for each spouse aged 65 or over, plus the senior deduction of $6,000 each, is $47,500.

Three things stand out. First, the worst zone is not at the bottom: for the single filer it is the narrow stretch where the 22% bracket meets the 85% band, with the senior deduction fading at the same time. Second, there is a cliff-free exit: once 85% of benefits is taxed, the marginal rate falls back to the bracket (12% for the couple), so a large one-year event can be cheaper per dollar than a series of small ones. Third, the senior deduction raises your taxable income by 6 cents (single) or 12 cents (a couple with both spouses aged 65 or over) for each extra dollar of AGI above $75,000 or $150,000, for taxable years before 2029.

Rental, REIT, K-1, Roth conversion, property sale: nine scenarios

The base couple is both aged 65 or over, files jointly, receives $60,000 of Social Security, and has $40,000 of other income ($36,000 of IRA distributions and $4,000 of taxable interest). They start inside the band: $28,100 of benefits taxable (46.8%), AGI $68,100 and federal tax of $2,060. Each row adds one thing (our assumptions) and shows what the Social Security test and the tax return do.

Source: our arithmetic (our script), 2026 brackets and standard deduction from Rev. Proc. 2025-32, senior deduction from IRC section 151(d)(5)(C), Social Security inclusion from IRC section 86 and Publication 915 Worksheet 1. Assumptions: standard deduction, no itemizing, no state tax, no credits, long-term gain taxed at 0%, 15% and 20% on top of ordinary income, unrecaptured section 1250 gain at no more than 25%. Scenarios C and D include a section 199A deduction of 20% of the $15,000 and $12,000 shown. “Extra tax” is the whole change from the base, including the effect on the senior deduction. “Of it, from more benefits” is that change minus what the same addition would cost if taxable benefits stayed at $28,100.

What the table says:

• Rental (B) and REIT with return of capital (C) land on the same Social Security number. Both add $18,000 to AGI, so both take taxable benefits from $28,100 to $43,400. The REIT paid $30,000 in cash, and the $12,000 return of capital cost nothing in the test. The federal tax differs by $720: a 199A deduction of $3,000 and a $3,000 capital gain distribution taxed at 0% (our arithmetic).
• C2 shows the catch. Once basis is gone the same $12,000 is a capital gain. Taxable benefits go from $43,400 to $51,000, $7,600 more, and the federal tax from $5,252 to $6,164, $912 more.
• K-1 income counts as taxable, not as cash (D). Of $30,000 distributed, $12,000 is taxable income here. The 199A deduction is $2,400 and has no effect on benefits.
• The Roth conversion (E) moves benefits to the ceiling. Of its $8,664 extra federal tax, $2,748 exists only because $22,900 more of benefits became taxable. Spread over $50,000 of conversion that is 17.3% overall (our arithmetic). Our Roth conversion guide covers the income-tax side and the illiquid-asset problem.
• A sale (F) is capped on the benefits side but not elsewhere. Benefits stop at $51,000 once other income passes $66,941, so the sale adds no more benefit tax. AGI is $211,000, $7,000 under the $218,000 first IRMAA threshold in the SSA table for premium year 2026 (the 2028 table is not published). Without the $22,900 of extra taxable benefits it would be $188,100. Below $250,000 the 3.8% net investment income tax is zero here.
• Municipal interest (G) is not free. Ten thousand dollars of tax-exempt interest adds $8,500 of taxable benefits and $936 of tax in this example, although the interest itself is untaxed. It also appears in MAGI for IRMAA ($86,600).

Withholding, forms and the filing mechanics

• Where it goes. Net benefits go on Form 1040 line 6a and the taxable part on line 6b; the line 6b amount is part of the line 9 total income and of AGI on line 11a. Line 6d is a check box for married filing separately and lived apart all year.
• Which worksheet. Use the Social Security Benefits Worksheet in the Form 1040 instructions or Worksheet 1 in Publication 915. Publication 915 requires Worksheet 1 if you exclude savings-bond interest (Form 8815), adoption benefits, foreign earned income or American Samoa or Puerto Rico income, and sends people with a traditional IRA deduction and a workplace plan to Appendix B of Publication 590-A.
• Publication 915 edition. The current edition is for 2025 returns. The edition for 2026 returns arrives after the year ends; the statutory amounts and the worksheet logic used here are the ones it will carry unless Congress acts. The line numbers in the 2025 forms may shift for 2026.
• Withholding. SSA lets you choose to withhold 7%, 10%, 12% or 22% of each monthly payment. If you have rental, K-1 or fund income with no withholding, see our estimated-tax guide.

What a reader can do with this

• Find your own line before the year ends. Add up AGI before Social Security (use last year’s return as a starting point), add tax-exempt interest and half your benefits, and compare with $25,000 or $32,000 and $34,000 or $44,000. The six-line method above does it.
• Find which band you are in. The marginal rate on the next dollar is different in the 50% band, the 85% band and above the ceiling, and a $5,000 decision can cost 12% or 22.2% of the same dollar.
• Check the type of every distribution on your forms. Sort each Form 1099-DIV box and each K-1 into “counts” and “does not count” using the table above. A box 3 amount is not income, but it lowers basis, and the basis you have left decides when it starts to count.
• Remember what a sale and a conversion do beyond the band. The Social Security tax stops at 85% of benefits, while IRMAA, the net investment income tax and the senior-deduction phase-out do not. A planner or CPA can run the whole return.
• Mind the calendar. A Roth conversion is a tax-year event that must be completed by December 31, 2026 to count for 2026. A fund’s Form 1099-DIV and K-1 arrive after year end, so the type of its 2026 distributions may not be known until then.
• Ask whether timing helps. Our arithmetic shows that spreading income over several years does not always cost less. It depends on where each year lands against the band.

This is analysis of public documents, not investment, legal or tax advice.

FAQ

Sources, read and saved on October 20, 2026: IRC sections 62, 86, 151(d)(5)(C), 199A, 469 and 1411 (law.cornell.edu/uscode); IRS Publications 915, 550 and 590-B (2025); Instructions for Form 1040 (2025), Instructions for Form 1099-DIV (Rev. 1-2024); Form 1040, Schedule 1, Schedule 1-A and Schedule E (2025); Rev. Proc. 2025-32; SSA POMS HI 01101.010 (effective December 2, 2025); the SSA page on requesting tax withholding (ssa.gov). The scenario figures, breakpoints and marginal rates are our arithmetic from the formulas shown on this page.