Quarterly estimated tax in Montana (2026)

A sole proprietor in Montana with $100,000 of profit pays the IRS about $5,032 a quarter, and owes $3,890 of Montana income tax for the year. Put in your own profit to get the four payments and their dates.

$5,032 a quarter

to the IRS. Four payments make $20,128 for the year, which meets 90% of this year's tax. This year's federal tax on this profit: $22,365 (income tax $8,235, self-employment tax $14,130).

Montana, 2026: $100,000 profit, single filer

IRS due	Income earned	IRS	Montana due	Montana
April 15, 2026	January 1 to March 31	$5,032	April 15, 2026	$875
June 15, 2026	April 1 to May 31	$5,032	June 15, 2026	$875
September 15, 2026	June 1 to August 31	$5,032	September 15, 2026	$875
January 15, 2027	September 1 to December 31	$5,032	January 15, 2027	$875
Year		$20,128		$3,500

Montana payments cover 90% of this year's state tax of $3,890, split 25%, 25%, 25%, 25% (Form IT (Montana Individual Income Tax Payment Voucher)). revenuefiles.mt.gov, checked Oct 23, 2026 Estimates assume a single-member business with no withholding.

Montana estimated tax rules for 2026

If your Montana tax after withholding comes to $500 or more, the state wants estimatesrevenuefiles.mt.gov, checked Oct 23, 2026.
Pay by April 15, 2026, June 15, 2026, September 15, 2026, January 15, 2027revenuefiles.mt.gov, checked Oct 23, 2026.
You avoid the penalty by paying 90% of this year's tax, or 100% of last year'srevenuefiles.mt.gov, checked Oct 23, 2026.
Send them with Form IT (Montana Individual Income Tax Payment Voucher), or pay on the state's website.

Payments at each profit

Profit	IRS each quarter	Montana for the year
$50,000	$2,190	$1,284
$100,000	$5,032	$3,501
$150,000	$8,462	$5,864
$250,000	$14,931	$10,736
$500,000	$37,574	$23,279

A sole proprietor or single-member LLC, single filer, no withholding, paying 90% of this year's federal tax and the state's own safe-harbor share.

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