If you work for someone else, tax comes out of every paycheck and you never think about it. When you work for yourself, nothing is withheld from anything — but the expectation that tax gets paid throughout the year does not go away. It just becomes your job to do it, four times a year, on dates nobody reminds you about.
Here is who this applies to, when the payments are due, how to work out a number that keeps you out of penalty territory, and what to do if a deadline has already gone past.
Who actually has to pay
The general rule is a threshold, not a business type: if you expect to owe roughly $1,000 or more when you file, after subtracting any withholding and refundable credits, you are expected to pay in during the year. That catches most sole proprietors, single-member LLCs, partners in a partnership, and shareholders taking distributions from an S corporation.
It is worth understanding what you are prepaying, because it is usually two things rather than one. There is income tax at your ordinary rate. There is also self-employment tax, which covers the Social Security and Medicare an employer would otherwise pay half of — the Social Security portion applies to net self-employment earnings up to an annual wage cap that adjusts every year, and the Medicare portion has no cap at all. Owners who budget only for income tax are the ones who get an unpleasant surprise in April, because at modest income levels the second piece is often the larger of the two.
One useful exception: if you or a spouse also holds a W-2 job, you can raise the withholding on that paycheck instead of writing quarterly checks. Withholding is treated as though it were paid evenly across the whole year no matter when it actually came out, which means a bump in the fall can cover a shortfall from the spring. Estimated payments get no such treatment — each one is credited to the period you actually made it in.
The four deadlines, and the periods they cover
For the 2026 tax year the payments are due April 15, June 15 and September 15 of 2026, and January 15 of 2027. When one of those dates lands on a weekend or a holiday it shifts to the next business day.
The word quarterly is misleading, and the mismatch trips people up. The periods are not three months each: the first payment covers January through March, the second covers only April and May, the third covers June through August, and the last covers September through December. So the June payment comes due after two months of income and the January one after four. If you set aside a percentage as money arrives, that unevenness does not matter. If you calculate each payment from a period total, it matters a great deal — treating the second period as a full quarter overstates it by a third.
Two ways to arrive at a number
The safest method is the prior-year safe harbor. Pay in, across the four installments, at least 100 percent of what your total tax was last year — 110 percent if your adjusted gross income last year was over $150,000 — and you are protected from an underpayment penalty even if this year turns out far better and you owe considerably more in April. You still owe the balance when you file; you simply are not penalized for the timing. This is the method to use when income is unpredictable, because it depends only on a number already sitting on last year’s return.
The other method works from this year: estimate your full-year profit, calculate the tax on it, and pay 90 percent of that across the four dates. Better for cash flow when this year is clearly worse than last, and the only sensible option in your first year of business, when there is no prior return to lean on. It does require books that are genuinely current, because you are extrapolating from your own numbers.
There is a third path worth knowing about if your income is seasonal or lumpy — a large project in the fall, a trade that goes quiet over the winter. The annualized income installment method lets you size each payment to what you actually earned in that period instead of paying four equal amounts, so you are not sending money in April against income you have not made yet. It takes an extra schedule at filing time to show the work, and your tax preparer can tell you whether it is worth the trouble in your situation.
Two things that are easy to forget: most states with an income tax run their own estimated payment system, with its own deadlines and thresholds, and the federal safe harbor does nothing for you there. And if you are an S corporation shareholder already on payroll, the withholding from your salary counts toward all of this — you are usually only estimating on the distribution side.
If you already missed one
Pay it as soon as you can rather than rolling it into the next installment. The underpayment penalty is calculated like interest accruing per period, so a payment three weeks late costs meaningfully less than the same payment three months late. There is no benefit whatsoever to waiting for the next official date.
The reason a missed payment turns into a bad April is rarely the penalty, which is often modest. It is that the money got spent. Moving a fixed percentage of every deposit into a separate account the day it arrives — before it starts feeling like working capital — does more to prevent the problem than any calculation method does. Your accountant can tell you what percentage is realistic for your bracket and state once, and after that it is just a habit.
All of this rests on knowing what you actually earned, which is a bookkeeping question before it is a tax question. Estimating from books that stop in February is guesswork; estimating from books closed through last month is arithmetic. That is the part we handle. Evolv Bookkeeping is $199 per month flat — every account reconciled, transactions categorized, and your P&L and Balance Sheet closed and delivered by day 2 of the following month, with 1099 prep at year end. If you are behind, catching up a backlog is a flat $500 one time however far back it goes, finished within 2 days and guaranteed in writing. No contracts, cancel anytime, and there is an instant quote on our homepage.