Yes, in most cases. When clients and coaching apps pay you with nothing withheld, the IRS still wants its money during the year, not in one lump the following April. That is what quarterly estimated payments are: you sending in your own withholding.
The $1,000 rule that triggers estimated payments
The trigger is simple. If you expect to owe $1,000 or more in total federal tax for the year, after subtracting any withholding from a day job, you are expected to pay estimates. For a full-time coach, that threshold arrives fast: between income tax and 15.3% self-employment tax, even a modest coaching profit clears $1,000 in tax. A part-time coach with a W-2 job can sometimes avoid estimates by raising withholding at work instead, which counts as if it were paid evenly through the year.
There is a safe harbor worth knowing. Pay in at least 100% of last year's total tax (110% if your prior-year income was high) or 90% of this year's tax, spread across the quarters, and you will not owe an underpayment penalty even if you end up owing more in April. First profitable year coaching? Matching last year's small tax bill can legally keep your required payments low while cash is tight.
Four deadlines every coach should put in their calendar
Estimated payments go in with Form 1040-ES, and the quarters are uneven, which surprises people. Payments are due Apr 15, Jun 15, Sep 15, and Jan 15 of the next year. The second period is only two months long, so June sneaks up on coaches every year. If a due date lands on a weekend or holiday it rolls to the next business day. You can pay online through the IRS rather than mailing vouchers, and most coaches should.
Estimating the amount does not require perfection. Take your coaching revenue for the quarter, subtract real expenses, and apply your combined rate. For many coaches, setting aside 25% to 30% of net income and sending it in each quarter lands close enough, then the annual return trues everything up.
What happens when a trainer skips a quarter
The penalty for underpaying estimates is essentially interest on the shortfall, calculated per quarter at a rate the IRS updates. It is not catastrophic, but it is pure waste, and it compounds with the cash-flow shock of a large April bill you did not plan for. Coaches who get behind one year often stay behind, because April's balance due and the current year's first estimate hit at the same time on Apr 15.
The fix is mechanical, not motivational. Open a separate savings account, move a fixed percentage of every payout into it the day the payout lands, and pay each quarter from that account. Do not skip a quarter because revenue dipped; recalculate and send the smaller, correct amount instead. Consistency is what keeps the penalty at zero.