The Blueprint · Part 4 of 4 · 12 min read
Money and taxes: quarterly payments and the year-end packet
Nobody withholds tax from a client payment. That's the whole surprise. The money shows up looking like income, and about a third of it isn't yours. And if the business does well enough, the government would like its cut four times a year instead of once. This part is the unglamorous machinery that keeps a good year from turning into an April problem.
Every number in this series can be worked out in Rotor Rate — free, no signup.
What you actually owe (and why it's more than you expected)
As a sole proprietor or single-member LLC, you report the business on Schedule C with your personal return, and you pay two separate taxes on the profit. Income tax at your normal bracket, plus self-employment tax — 15.3% of net earnings, covering both halves of Social Security and Medicare. When you had an employer, they quietly paid half of that for you. Now you're both. It kicks in once net self-employment earnings hit $400. That combination is why 'set aside 25-30% of every payment' is the standard advice: it's about right for most new operators, and it beats setting aside nothing by a mile.
Estimated quarterly payments: who, when, how much
If you expect to owe at least $1,000 in tax for the year, the IRS wants it in installments as you earn it. Four payments — and despite the name, they aren't evenly spaced. The deadlines land in April, June, September, and the following January. The safe-harbor rule is the part worth memorizing: pay at least 90% of what you'll owe this year, or 100% of what you owed last year (110% if your adjusted gross income was over $150,000), and you dodge the underpayment penalty even if you guessed low. If you still have a W-2 job, there's a lazier option: raise your withholding there and skip the quarterly checks entirely.
| Payment | Covers income earned | Due |
|---|---|---|
| 1st | January 1 – March 31 | April 15 |
| 2nd | April 1 – May 31 | June 15 |
| 3rd | June 1 – August 31 | September 15 |
| 4th | September 1 – December 31 | January 15 (following year) |
Pay it in two minutes
Both are free and official. Direct Pay is fine for a one-off; EFTPS is better if you want a schedule.
- IRS Direct Pay — Pay an estimated instalment straight from your bank account
- EFTPS — schedule payments in advance — Set all four quarters up once
- IRS — Estimated taxes, who must pay — Current due dates and the safe-harbour rule
- Search: state estimated tax payments — Add your state — many run their own schedule
The separate-account habit does the bookkeeping for you
Open a second savings account and move your tax percentage into it the day each payment lands. Not monthly. Not 'when I get around to it.' The same day, every time. Operators who do this find quarterly payments boring, and operators who don't find them terrifying. The whole difference is plumbing. Same goes for the business checking account from Part 1: when every business dollar runs through one account, your books are a statement download instead of a memory test.
The monthly ten minutes
- 1
Move the tax percentage to the tax account
25–30% of profit is a reasonable default until an accountant gives you a better number.
- 2
Log expenses and attach receipts
Photograph the receipt at the register; the paper one will fade or vanish.
- 3
Reconcile mileage
Every business trip, with date, miles, and purpose.
- 4
Chase anything overdue
Unpaid invoices and network payouts you're still owed.
- 5
Glance at profit for the month
Not for fun — it's what tells you whether to raise prices.
Deductions new operators leave on the table
Mileage is the big one. The standard mileage rate for 2026 is $0.725 per business mile, and it's real money — a hundred-mile job week adds up to thousands over a year. What the IRS wants in return is a log kept as you go: date, destination, business purpose, miles. Not a reconstruction from your camera roll in April. Past mileage: the aircraft and payload (often expensed in year one instead of depreciated), batteries, memory cards, software subscriptions, insurance, your certificate and recurrent training, LAANC and mapping apps, the website and phone, the business-use share of your home internet, and the home-office deduction if a space in your home is used regularly and exclusively for the business. That word 'exclusively' is where people get themselves in trouble — the kitchen table doesn't count.
Claim them properly
- IRS — current standard mileage rate
- Download the free mileage log template — Date, purpose, miles — the columns the IRS wants
- IRS Publication 463 — what a compliant log contains
- IRS — Home office deduction — The 'regular and exclusive use' test
Side hustle or full time — the same rules, different maths
There's no special tax regime for a side hustle. A weekend operator making $6,000 files the same Schedule C as the full-timer; the difference is your W-2 withholding may already be covering enough to keep you out of quarterly payments. Going full time changes three things worth planning for: health insurance becomes your line item, income gets seasonal in a way a salary never was, and quarterly payments stop being optional. The standard advice is three to six months of personal expenses banked plus a base of repeat work — retainer-style progress documentation, recurring inspection routes — before you resign. Watch your own profit trend for two or three quarters. That signal beats any article's threshold, including this one.
The year-end packet: what your accountant actually wants
In January, a good accountant wants four things: total income by source, categorized expenses, your mileage log, and last year's return. That's it. What they don't want is a shoebox, a folder of screenshots, or a text saying 'roughly forty grand I think.' Hand them clean exports and you'll pay for an hour of advice instead of three hours of data entry — and the advice is where the value is, including whether an S-corporation election starts making sense as profit grows. Do the export in the first week of January while the year is still fresh, not in April.
Your January folder
- 1
Income export
Every mission and invoice with date, client or network, and amount received.
Export from Rotor Rate - 2
Expense export by category
Gear, software, insurance, travel, training, fees — with receipts attached.
- 3
Mileage report
Total business miles with the underlying log behind it.
- 4
1099s as they arrive
Networks and larger clients send them; your own records should already match.
- 5
Bank and card statements
Twelve months, business account only.
- 6
Last year's return and any estimated payments made
So your accountant can check the safe harbour and set next year's instalments.
See your IRS payment history
Find someone to hand it to
- IRS directory of credentialed tax preparers — Search CPAs and enrolled agents by ZIP code
- IRS — About Schedule C — The form your profit lands on
- Free SBDC advisor to review your books — University-hosted, no charge
Where this leaves you
Four parts ago you had a certificate. Now you've got a registered business, insurance a client will accept, a price with arithmetic behind it, work coming through both doors, and a set of habits that make tax season a download instead of a crisis. Keep the machinery running — log every job, move the tax money the day it lands, look at profit monthly — and the business compounds quietly while you focus on flying. That's the whole trick. Almost nobody does it.
The habits that keep this running
- 25–30% of every payment moved to a separate tax account the day it lands.
- Estimated payments diarised for April, June, September and January — or W-2 withholding raised instead.
- Mileage logged contemporaneously, with date, purpose and miles.
- Expenses categorised monthly with receipts attached.
- A January export: income, expenses, mileage, statements — one folder, one email to your accountant.
Sources & further reading
Rules change. These are the primary sources behind this part — check them against your own state and tax year before you act.
- IRS — Self-employment tax (Social Security and Medicare) — The 15.3% rate and the $400 net-earnings threshold.
- IRS — Estimated taxes — Who must pay, the four due dates, and the safe-harbour rules.
- IRS — About Schedule C (Form 1040) — How sole proprietors and single-member LLCs report profit or loss.
- IRS — Standard mileage rates — Official per-mile business rate by tax year.
- IRS Publication 463 — Travel, Gift, and Car Expenses — What a compliant mileage log must contain.
- IRS — Home office deduction — The 'regular and exclusive use' test.
- IRS — Recordkeeping for small business — How long to keep records and what counts as proof.
- SBA — Pay taxes — Federal and state tax obligations by business structure.
- America's SBDC — free local advising — University-hosted centers that will review your books and projections at no cost.