1099 and self-employed. 2026 tax year.
Nobody withholds anything from a 1099. You get the gross amount and are expected to send the IRS its share four times a year, at a size you estimate yourself. That estimate is built on net profit, so every expense you can document pulls it down twice over.
The calculator is free and runs in your browser. No account, no email address, nothing sent to a server. The app itself is 79.99 a year or 12.99 a week and is not on the App Store yet.
The 2026 calendar
The dates are fixed and published a year ahead. What catches people out is that the periods behind them are not equal quarters.
| Payment | Due date | Income it covers |
|---|---|---|
| 1st | April 15, 2026 | January 1 to March 31, 2026 |
| 2nd | June 15, 2026 | April 1 to May 31, 2026 |
| 3rd | September 15, 2026 | June 1 to August 31, 2026 |
| 4th | January 15, 2027 | September 1 to December 31, 2026 |
Read the right column twice. The second payment covers two months, not three, and the fourth lands in January of the next year. In late August 2026 the payment in front of you is the third, due September 15, covering June 1 through August 31.
Estimated payments exist because nobody withholds for you. A W-2 employee has tax taken out before the money arrives. A 1099 contractor becomes the withholding department. The IRS covers the mechanics on its estimated taxes page, and the worksheet behind the four numbers sits inside Form 1040-ES.
Rather not fill in a worksheet? The DeductHound calculator asks what you expect to make and what you have tracked so far, then shows the four payments with a source for every rate.
The rule that decides the penalty
Safe harbor is not about guessing well. It is a floor: clear it and an underpayment penalty is off the table, whatever the year turns out to look like.
Form 1040-ES for 2026 sets the test. Your payments are far enough along if they reach any one of these:
The middle route is the quiet favorite, because you already know that number. It is printed on the return you filed. Divide it by four and send it four times.
Clear none of the three and the shortfall is computed on Form 2210. The IRS describes how the underpayment of estimated tax penalty works, and the detail worth keeping is that it runs period by period, so a light payment in June is not repaired by a heavy one in January.
Safe harbor protects you from a penalty, not from the bill. Take the 100% of last year route in a year that goes much better and the difference is still owed when you file. Worth opening the calculator again in December.
Why this page is about paper
Here is the part most quarterly tax articles skip. What you send in is built on net profit, and net profit is revenue minus the expenses you can document. Two separate taxes read that one figure.
The self-employment tax rate is 15.3%, 12.4% for social security plus 2.9% for Medicare, applied to 92.35% of net profit rather than to what your clients paid you. The social security part stops at 184,500. Medicare does not stop, and an additional 0.9% starts at 200,000 for single filers and 250,000 for married filing jointly.
That same profit figure carries on to your 1040, where the 2026 standard deduction is 16,100 for single filers, 32,200 for married filing jointly and 24,150 for head of household. One profit line, two taxes reading it.
An expense you cannot produce a record for is not going on any line of any form. The IRS is blunt about it in its guidance on what records to keep: expenses have to be ordinary and necessary, and you have to be able to show them. Whether a purchase belongs on your Schedule C is a question for a tax professional. Whether you still have the paper is a question for you.
So the shoebox is not a filing problem waiting for April. It is a cash flow problem happening now. A payment estimated from an incomplete expense record is estimated from a profit figure larger than the one you earned, and you wire that difference to the IRS months before anyone asks whether it was right.
The fix is arithmetic. Run your year in the calculator with the tracked total you have today, then run it again with the total you would have if the shoebox and the camera roll were logged. The gap is what a quarter of tracking is worth to you, in dollars, and it is the whole case for a tax write-off tracker, ours included. Nothing here promises you a deduction. It says something narrower: you cannot claim what you cannot document, and September 15 does not wait.
Expected profit, filing status, what you have tracked so far. Out comes the self-employment tax, the income tax estimate and the four payments for 2026, with the IRS page behind every rate. Free, no signup, nothing leaves your browser.
What DeductHound does about it
The app does not file anything, does not connect to your bank and does not tell you what is deductible. It turns paper into a categorized, exportable list.
Batch import takes the receipts already sitting in your camera roll, processes them in one pass and queues them for confirmation. More on the expense tracker page.
Total, date, merchant, sales tax and tip, each one editable beside the photograph it came from. The reading happens on the iPhone, so it works in airplane mode. Detail on the receipt scanner page.
CSV and PDF by quarter, year or any range, every row tagged with the real line number from the Schedule C instructions. Advertising line 8, Supplies line 22, Meals line 24b. The mapping is on the Schedule C expenses page.
A lock screen widget with the countdown and a reminder before each estimated tax date. Zero of the thirty apps we measured in this category ship widgets.
Questions
Two things decide it. The first is whether you owe self-employment tax at all, and the IRS puts that line at 400 of net earnings. The second is whether enough is already covered another way, by a day job's withholding or a spouse's. The estimated taxes page is the short version and Form 1040-ES holds the worksheet.
Nothing dramatic happens on the day. The shortfall is computed later on Form 2210, period by period, and the IRS explains it on its page about the underpayment of estimated tax penalty. Pay as soon as you can, because the calculation runs from the due date. The full sequence is in what to do after a missed quarterly tax deadline.
Pick a safe harbor route and divide by four. Form 1040-ES gives you 90% of the tax you owe for 2026, or 100% of the tax on your 2025 return, or 110% of that figure if your adjusted gross income last year was over 150,000. The calculator works the current year route.
The periods are not equal quarters to start with, as the table above shows. For a front loaded or back loaded year, the annualized income installment method on Form 2210 lets the payments follow the income, and the IRS mentions it on the underpayment penalty page. Ask a tax professional whether it fits your year.
It changes the net profit figure the estimate is built from, and both taxes read that figure. What no app can do is decide anything for you. DeductHound records and totals what you enter under the category you pick, with the line number from the Schedule C instructions beside it. Keeping the evidence, per the IRS guidance on recordkeeping, is the part that is yours.
No. There is no payment feature, no bank connection, no filing and no account to create. You pay the IRS directly and the routes are on the estimated taxes page. The app hands you a categorized quarter with the Schedule C line next to each total. The rest of what it does is on the home page.
No newsletter, no drip sequence, no discount codes. A single message when DeductHound reaches the App Store. Until then the calculator is free and asks nothing of you.
Checked on August 25, 2026
Every figure on this page is quoted from one of these.