← Quarterly Estimated Tax Calendar
The missed quarter's requirement doesn't disappear and it doesn't reset --
it stays open on the running total the IRS safe harbor measures against,
until you actually pay it. How much the next payment needs to be depends
entirely on how many more due dates pass before you catch up. Worked with
this calculator's own example numbers below, and every figure is checked
against calc.mjs in this page's test file.
This calculator's own "Load an example" button sets a freelancer who owed $9,500 last year on an $85,000 AGI, with nothing withheld and nothing paid yet. That AGI is under the $150,000 high-income threshold, so the safe harbor is 100% of last year's tax, split evenly across four quarters: $2,375 per quarter. For the 2026 tax year, Q1 is due April 15 and Q2 is due June 15.
Say Q1's April 15 due date passes with nothing paid. If you catch it any time before Q2's June 15 due date arrives, only Q1 is counted as actually due so far -- the running total required is $2,375, nothing has been paid against it, and the one catch-up payment needed is $2,375. That's the same amount Q1 always needed; paying it late instead of on time doesn't add anything to the dollar figure by itself.
Now say nothing gets paid before Q2's due date passes either. By that point two quarters are counted as due -- a running total of $4,750 -- and still nothing has been paid against it. The single catch-up payment needed to get back on the safe-harbor pace is now $4,750, not $2,375: two quarters' worth in one payment, because the requirement that was already open from Q1 didn't go away when Q2's own share came due -- it stacked.
| Point in time | Quarters counted as due | Paid so far | Catch-up payment needed |
|---|---|---|---|
| Before Q2's due date, Q1 still unpaid | 1 (Q1 only) | $0 | $2,375 |
| After Q2's due date, both still unpaid | 2 (Q1 and Q2) | $0 | $4,750 |
Every additional due date that passes with nothing paid adds another $2,375 -- one full quarter's flat share -- to that single number, for as long as the running total stays unpaid.
This is the part a flat reminder -- "pay $2,375 every quarter" -- can't catch. Say a filer misses Q1, then simply sends the normal $2,375 for Q2 on time, thinking that settles it. By Q2's due date, $4,750 is required and only $2,375 has been paid: they are still $2,375 short, exactly one quarter's share behind, even though a payment went out and landed on time. What matters is the running total paid against the running total required, not whether the most recent single payment matched the flat quarterly figure.
The catch-up figures above track only the IRS Form 1040-ES safe-harbor dollar amount -- the running total required against what's actually been paid. They are not the full cost of missing a payment: the IRS separately charges interest on an underpayment, computed under Form 2210, and that interest is not calculated on this page or by this calculator. Treat the numbers above as the floor of what catching up costs, not the whole bill.
Nothing is forgiven and nothing resets. The IRS safe-harbor requirement for that quarter still exists; it just sits unpaid on the running total until you pay it. On this calculator's own worked example -- a filer who owed $9,500 last year on an $85,000 AGI, so a $2,375 flat quarterly share -- missing Q1 entirely leaves a $2,375 gap that stays open until it's paid, whichever quarter you finally send it in.
If you catch it before the next quarter's own due date arrives, the make-up payment is just that one missed quarter's flat share -- $2,375 in this worked example, the same as if you'd paid it on time, just later. It only grows if you let more due dates pass without paying anything.
Yes. Each due date that passes with nothing paid adds another quarter's flat share to the one payment needed to get back on the safe-harbor pace. In the worked example, catching up right after missing Q1 costs $2,375; let Q2's own due date pass too before paying anything, and the single catch-up payment needed is $4,750 -- two quarters' worth, not one -- because the running total the IRS measures against keeps growing every quarter you don't pay.
No, and this is the mistake a flat reminder ("pay $2,375 every quarter") doesn't catch. A filer who missed Q1 and then sends the usual $2,375 for Q2 has paid $2,375 total against $4,750 actually required by that point -- still $2,375 behind, exactly one quarter's share short, even though a payment went out on time. The running total, not the single quarter, is what determines whether you're caught up.
No. This page and the calculator only track the safe-harbor dollar amount required by each due date against what's actually been paid, and size a catch-up payment from that. The IRS charges interest on an underpayment separately, computed under Form 2210, and that interest is not shown here -- the practical effect for a filer is that the catch-up amounts on this page are the floor, not the full cost of waiting.