Quarterly Estimated Tax

Calculate what to send the IRS each quarter. Avoid underpayment penalties.

Expected net self-employment profit this year $120,000

Revenue minus business expenses, before any tax.

Tax already withheld or paid this year $0

Include W-2 withholding from a day job and any estimated payments already sent.

Federal marginal rate 22%

State rate 5%

Quarters remaining this year 4

Send each quarter

$0 total estimated for the year, $0 remaining after payments

Self-employment tax

15.3% on 92.35% of profit

Income tax, federal + state

at 22% federal and 5% state

Payment schedule by due date

💡 Set-aside rule

Set aside about 0% of every dollar you earn.

Solo 401k vs SEP IRA Calculator

Both plans let an owner with no employees shelter a large share of profit from tax, but they are not the same size. A SEP IRA is employer money only: 20% of net profit for a sole proprietor or LLC, 25% of W-2 salary for an S-Corp. A Solo 401k takes that same employer share and adds an employee deferral on top, and at most incomes the deferral is the entire difference. Owners often default to the SEP because a bank opened one in five minutes, and at $80,000 of profit that habit leaves about $24,500 of room unused every year.

Enter your net self-employment profit (the label switches to W-2 salary when you select S-Corp), your age, your marginal tax rate, and your business structure. The calculator applies 2026 IRS limits: a $24,500 employee deferral, a $72,000 overall cap, an $8,000 catch-up at age 50 and up, an $11,250 catch-up at ages 60 to 63, a $360,000 compensation cap, and the $184,500 Social Security wage base. For a sole proprietor it subtracts half of self-employment tax before taking the 20% employer share; for an S-Corp it takes 25% of salary. The headline is the extra room a Solo 401k gives you over a SEP IRA. The two stats are the SEP IRA maximum and the Solo 401k maximum, each with the tax saved at your rate. The insight box explains where the gap comes from.

The chart is a pair of stacked bars. The SEP IRA bar is a single sage block for the employer contribution. The Solo 401k bar stacks the employer share in sage, the employee deferral in gold, and any catch-up in muted green. A tall gold block on a short sage base is the typical picture for income under about $250,000. As profit climbs toward $360,000 the employer share alone hits the $72,000 cap, the bars converge, and only the catch-up remains.

Predictable Income treats investing as the third income stream and the business as the engine that funds it, so the plan you choose is a system decision: more pre-tax room means more dollars compounding for the stream that eventually replaces the other two. Run the numbers before you open an account, not after. Re-run each January when limits reset, whenever profit changes, when you turn 50 or 60, and if you convert to an S-Corp.