Yes. If clients pay you directly, through a coaching app, or through your own site, and no employer withholds taxes from those payments, the IRS treats you as self-employed. That means self-employment tax on your net coaching profit, on top of ordinary income tax.
The 15.3% that replaces employer withholding
Employees split Social Security and Medicare with their employer: each side pays 7.65%. A self-employed coach is both sides, so the combined rate is 15.3% of net earnings, 12.4% for Social Security and 2.9% for Medicare. The Social Security portion only applies up to an annual wage base that changes each year, so check the current IRS figure if your profit is well into six figures. The Medicare portion has no cap.
The tax applies to profit, not revenue. If you collected $60,000 in coaching payments and spent $12,000 on certifications, app subscriptions, gym rental, and equipment, self-employment tax is figured on the $48,000 that is left. Every legitimate write-off you track lowers this tax directly, which is why bookkeeping matters more for coaches than most people expect.
Schedule C and Schedule SE, the two forms that do the math
Your coaching income and expenses land on Schedule C, which produces your net profit. That number flows to Schedule SE, which calculates the self-employment tax. Both attach to your Form 1040. Two details soften the blow: you compute the tax on 92.35% of net profit rather than the full amount, and you deduct half of the self-employment tax you pay when figuring your income tax. Neither makes the tax small, but both are built into the forms, so you get them automatically.
If you also have a day job with a W-2, your job withholding covers that paycheck only. The coaching profit still generates self-employment tax, and your job's Social Security withholding only reduces the 12.4% portion if your combined earnings pass the wage base.
The $400 threshold that catches side-hustle coaches
Self-employment tax starts once net earnings from self-employment hit $400 for the year. That is not a typo. A trainer who cleared $1,500 selling a few program blocks on the side is over the line and owes the tax, even if no platform sent a 1099. The obligation follows the income, not the paperwork.
Because nothing is withheld during the year, coaches who owe $1,000 or more in total tax are expected to pay quarterly estimates with Form 1040-ES, due Apr 15, Jun 15, Sep 15, and Jan 15. A workable habit: set aside 25% to 30% of every payout in a separate account the day it lands, then send estimates from that account each quarter. That way the 15.3% never sneaks up on you in April.