Quarterly estimated taxes: the bill nobody warns new owners about

When you had a job, tax came out of every paycheck and April was mostly paperwork. The day you start earning through your own business, that stops. Nobody withholds anything, and the IRS does not wait until April to be paid.

How it works

The federal system is pay-as-you-go. If you expect to owe a meaningful amount of tax for the year after any withholding, you pay it in four instalments during the year. The usual due dates are April 15, June 15, September 15 and January 15 of the next year. Most states with an income tax run a similar schedule.

If you are an owner of an LLC taxed as a sole proprietorship or partnership, the profit flows onto your personal return. That profit is what the estimates are based on, along with self-employment tax.

The penalty is small, the cash shock is not

Missing estimates usually costs an underpayment penalty, calculated a bit like interest. It is rarely ruinous. The real damage is the April bill: a full year of tax on business profit arriving at once, in a month you did not plan for.

A simple way to stay ahead

Open a separate savings account and move a fixed share of every payment you receive into it the day it lands. Many owners use somewhere between a quarter and a third of profit as a starting point, then adjust once they see their real number. When an estimate is due, the money is already sitting there.

Your accountant can tell you whether a safe-harbour approach suits you - basing this year's estimates on last year's total tax is a common one, because it protects you from the penalty even when this year turns out better than expected.

Where an S corp election changes things

If your business elects S corporation tax treatment, you pay yourself a salary through payroll, and tax is withheld from that salary like any job. Distributions on top of salary still flow to your return, so estimates do not disappear entirely - but the payroll side is handled every pay period.

The habit that matters

Set reminders for the four dates. Keep the tax account separate from the operating account so the money is never spent by accident. And check your numbers mid-year: a quarter that is much better or worse than expected is the moment to adjust the next payment, not next April.