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How Self-Employment Tax Works in Montana (2026)
Self-employment tax is 15.3% — 12.4% Social Security plus 2.9% Medicare — applied to 92.35% of your net self-employment income, on top of federal and Montana income tax. Half of the SE tax (7.65% equivalent) is an above-the-line deduction against your federal taxable income.
| Piece | Rate / rule |
|---|---|
| Net earnings subject to SE tax | 92.35% of net profit |
| Social Security portion | 12.4% (up to $184,500 of net earnings) |
| Medicare portion | 2.9% · +0.9% above $200,000 |
| Deductible half of SE tax | 50%, above-the-line on your federal return |
Estimated payments are due quarterly (roughly mid-April, mid-June, mid-September, and mid-January). The 20% Qualified Business Income deduction (§199A) is not modeled here — it depends on your income level and business type. If you also have W-2 wages, the Social Security cap is measured against your combined earnings, so this estimate runs high.
Montana Self-Employment Tax by Income (2026)
Single filer, 1099 income is the only earnings for the year. The quarterly figure is an even 4-way split of the annual total.
| Net 1099 income | SE tax | Federal tax | Montana tax | Quarterly payment |
|---|---|---|---|---|
| $20,000 | $2,826 | $249 | $608 | $921 |
| $40,000 | $5,652 | $2,281 | $1,481 | $2,353 |
| $60,000 | $8,478 | $4,511 | $2,355 | $3,836 |
| $80,000 | $11,304 | $7,527 | $3,228 | $5,515 |
| $100,000 | $14,130 | $11,616 | $4,102 | $7,462 |
Montana Self-Employment Tax FAQ
What are Montana's income tax brackets for 2026?
Montana uses 2 marginal brackets under HB 337: 4.70% up to $95,000 of taxable income, and 5.65% above that (single filers). Standard deduction: $5,660.
How much is take-home pay on $65,000 in Montana?
On a $65,000 gross salary, a single filer in Montana takes home roughly $51,618.52/year (about $4,301.54/month) after federal tax, FICA, and state tax.
What deductions does Montana apply before taxing my income?
Montana applies a $5,660 standard deduction, before its marginal bracket schedule. See the "How Montana Paycheck Tax Is Calculated" section above for the exact formula.
Does this estimate change if I'm married or have dependents?
This calculator uses single-filer figures only (v1 scope). Married filing jointly typically uses different federal and Montana state brackets and a larger standard deduction — your actual take-home pay will differ. Dependents can also reduce federal withholding via the W-4. Check Montana Department of Revenue's married-filing-jointly tables for a precise figure.
Methodology & Source
Montana state tax figures sourced from Montana Department of Revenue (https://mtrevenue.gov/), citing Mont. Code § 15-30-2103. Federal brackets, standard deductions (single/MFJ/HoH), and FICA constants sourced from the IRS (Revenue Procedure 2025-32; married-filing-jointly Additional Medicare threshold of $250,000 is a separate, unindexed statutory figure). Montana's married-filing-jointly and head-of-household figures are not yet independently verified and currently fall back to single-filer brackets — see the caveat in the formula section above.
Self-employment tax uses the statutory 15.3% rate (12.4% Social Security + 2.9% Medicare) on 92.35% of net self-employment income, with half of the SE tax deducted from federal taxable income above-the-line — per IRS Schedule SE (Form 1040) instructions, IRC §1401 and §164(f), 2026 edition. The 20% Qualified Business Income deduction (IRC §199A) is not modeled — it phases out by income and business type and is too state/entity-dependent to compute generically. This assumes the self-employment income is your only earnings for the year; if you also have W-2 wages, the Social Security wage-base cap and Additional Medicare threshold are actually based on your combined earnings, so this will overstate SE tax if you have significant wage income too.
This is an estimate based on standard single-filer federal, FICA, and MT state calculations. Actual withholding may differ based on your W-4 elections, pre-tax deductions, and other factors. Montana's standard deduction is actually 20% of AGI (min $2,830, max $5,660), not a fixed amount; this estimate uses the maximum, which understates tax for lower incomes.
Guideline version: 2026-MT-v2 · Effective: 2026-01-01 · Last verified: 2026-08-18