I'm a CPA — Here's the Simplest Way to Handle Quarterly Estimated Taxes
- Vani Murthy
- Jun 16
- 9 min read
Updated: Jul 2
If you've started freelancing or contract work in Arizona — or you've been at it a while and feel like you might be doing taxes wrong — this guide is for you. Quarterly estimated taxes are one of the biggest adjustments to being self-employed, and most people never get a clear explanation of how they work.
Table of Contents
Quick Answer
Why Do Quarterly Taxes Exist?
Who Needs to Pay?
The Payment Calendar
What Are You Actually Paying For?
Self-Employment Tax (Social Security & Medicare)
Federal Income Tax
Arizona Freelancers: Don't Forget State Taxes
The "Safe Harbor" Rule — Your Get-Out-of-Penalty Card
How to Actually Pay
How to Stay on Top of the Money
What Happens If You Miss a Payment?
Deductions Worth Knowing About
Frequently Asked Questions
Quick Summary
Key Takeaways
About the Author
Disclaimer
Quick Answer
Most Arizona Freelancers generally need to make quarterly estimated tax payments if they expect to owe at least $1,000 in federal taxes. Payments are usually due April 15, June 15, September 15, and January 15. A simple strategy is to save 25–30% of your income throughout the year and make payments using IRS Direct Pay.
Why Do Quarterly Taxes Exist?
When you had a regular job with a W-2, your employer took taxes out of every paycheck and sent them to the IRS for you. You might have owed a little more or gotten a small refund at tax time, but the heavy lifting was done automatically.
As a self-employed worker, nobody is doing this for you. You get paid the full amount from your clients, and it's your job to set aside money and send it to the government yourself. The IRS wants you to pay throughout the year — not all at once in April.
That's what quarterly estimated taxes are: paying your tax bill in four chunks instead of one lump sum.
Who Needs to Pay?
You need to make quarterly payments if you expect to owe $1,000 or more in federal taxes for the year. For most full-time freelancers and contractors, this threshold is pretty easy to hit.
If you still have a part-time W-2 job alongside your freelance work, the taxes taken from that paycheck might cover what you owe. If they don't, you'll need to make estimated payments to cover the gap. Same goes for state taxes — each state has its own rules, so check with your state's tax website.
The Payment Calendar
The IRS splits the year into four payment periods. They're not exactly equal quarters, so here's the cheat sheet:
Income You Earned | Payment Due |
January 1 – March 31 | April 15 |
April 1 – May 31 | June 15 |
June 1 – August 31 | September 15 |
September 1 – December 31 | January 15 (next year) |
If the due date lands on a weekend or holiday, it moves to the next business day. Put all four dates in your calendar at the start of the year and set a reminder a week ahead so you have time to figure out your payment.
What Are You Actually Paying For?
Your quarterly payment covers two things: self-employment tax and federal income tax. Let's walk through both with a real example — a freelance graphic designer who makes $60,000 in net income (revenue minus business expenses).
Self-Employment Tax (Social Security & Medicare)
When you were an employee, you and your employer each paid 7.65% toward Social Security and Medicare. As a self-employed person, you cover both sides — so the headline rate is 15.3%.
But here's the small break the IRS gives you: you only pay that 15.3% on 92.35% of your net income, not the full amount. Why? Because they're letting you deduct the "employer half" before calculating — same way a regular business would. Think of it as a built-in 7.65% discount off the top.
Using our $60,000 freelancer:
The IRS taxes $60,000 × 92.35% = $55,410 (that's the discount doing its work)
$55,410 × 15.3% = $8,478
Self-employment tax: $8,478 for the year.
In plain English: your effective self-employment tax rate works out to about 14.1% of your net income — not the full 15.3%.
Federal Income Tax
This is the same income tax everyone pays, self-employed or not. Using the same $60,000 freelancer — filing single with the standard deduction:
Taxable income: $60,000 − $14,600 (standard deduction) − $4,239 (half of self-employment tax is deductible) = $41,161
First $11,600 taxed at 10% = $1,160
Remaining $29,561 taxed at 12% = $3,547
Federal income tax: $4,707
Add them up:
What | Amount |
Self-employment tax | $8,478 |
Federal income tax | $4,707 |
Total federal tax bill | $13,185 |
Per quarter | ~$3,296 |
Now compare that to the "set aside 25%" shortcut:
25% of $60,000 = $15,000 saved → easily covers the $13,185 bill with a buffer for state taxes or income swings.
This is why the 25–30% rule works for most freelancers. Run the math once at the start of the year with your own numbers and you'll know exactly which percentage to use.
Arizona Freelancers: Don't Forget State Taxes
Arizona freelancers may also need to make Arizona estimated tax payments separately from their federal IRS payments.
Arizona has state income tax.
Federal payments do not cover Arizona taxes.
Set aside additional funds if needed.
Make Arizona estimated payments through the state system.
The "Safe Harbor" Rule — Your Get-Out-of-Penalty Card
This is one of the most helpful rules for self-employed people. The safe harbor rule protects you from penalties — even if you end up owing more at year-end.
You're safe from penalties if your total estimated payments equal at least:
100% of what you owed in taxes last year, OR
90% of what you owe this year
If your income last year was above $150,000, the first number bumps up to 110% of last year's tax bill.
In practice, most self-employed people use the "last year" option — especially if their income goes up and down. Take last year's total federal tax, divide by four, and pay that amount each quarter. You'll still need to pay any leftover balance at filing time, but you won't get hit with penalties.
How to Actually Pay
Federal payments can be made through:
IRS Direct Pay — free, no account needed, pays straight from your bank account
EFTPS — lets you schedule payments in advance
Check or money order with a Form 1040-ES voucher, mailed to the IRS
State payments go through your state's tax website. Most states have online systems similar to IRS Direct Pay.
How to Stay on Top of the Money
The hard part for most freelancers isn't understanding the rules — it's having the cash when payments are due.
Here's what works:
Open a separate tax savings account. When a client pays you, move 25–30% into that account right away. Do it before you spend anything else. That money is gone — treat it like it was never yours to begin with.
Track income and expenses as you go. Your tax is based on net income (what's left after business expenses), so good records help you make better estimates and legally lower your tax bill.
Check in each quarter. If your income changes — a big new client, a slow month, a major business expense — adjust your next payment. Don't wait until the end of the year.
What Happens If You Miss a Payment?
You won't get in legal trouble right away. But you will owe a penalty — roughly 8% per year on whatever you should have paid.
The penalty is calculated per quarter. So if you miss the April payment, penalties build up from April through December. The best move: pay as soon as you can and make sure the rest of the year's payments are on time.
Deductions Worth Knowing About
Lowering your net self-employment income through legitimate business deductions directly reduces what you owe. Common ones for freelancers:
Home office — if you use part of your home only and regularly for work
Health insurance premiums — deductible if you're not eligible for a spouse's employer plan
Business equipment and software — computers, tools, subscriptions
Professional development — courses, books, conferences related to your work
Business portion of phone and internet
Retirement contributions — SEP-IRA or Solo 401(k) contributions can make a big dent in taxable income
Keep good records throughout the year and these deductions are easy to claim at tax time.
Frequently Asked Questions
1. Do all freelancers have to pay quarterly taxes?
No. Generally, you should make estimated tax payments if you expect to owe at least $1,000 in federal taxes after credits and withholding.
2. How do I calculate my quarterly tax payments?
Many freelancers start by setting aside 25–30% of net income. For a more accurate estimate, use Form 1040-ES or work with a tax professional.
3. Can I skip a quarterly payment if income is low?
You can adjust payments based on income changes, but underpaying may result in penalties. Review your earnings each quarter and update estimates as needed.
4. What is the safe harbor rule?
The safe harbor rule helps you avoid underpayment penalties if you pay at least 100% of last year's tax liability (110% for certain higher-income taxpayers) or 90% of your current year's tax liability.
5. Should Arizona freelancers make state estimated tax payments?
Yes. Arizona estimated tax payments are separate from federal IRS payments. Depending on your income and tax situation, you may also need to make estimated payments directly to the Arizona Department of Revenue.
6. What happens if I overpay my quarterly estimated taxes?
If you overpay your estimated taxes, the extra amount isn't lost. The IRS generally applies the overpayment toward your tax return, where it can either reduce the balance you owe or be refunded to you after you file.
7. Can I change my estimated tax payments during the year?
Yes. Your estimated tax payments aren't set in stone. If your income increases or decreases significantly during the year, you can adjust future payments to better match your expected tax liability.
8. What if I miss a quarterly estimated tax payment?
Missing a payment doesn't usually result in severe consequences, but the IRS may assess an underpayment penalty and interest on the unpaid amount. Paying as soon as possible can help reduce additional charges.
9. Do business expenses reduce my quarterly estimated taxes?
Yes. Quarterly estimated taxes are generally based on your net business income after deductible business expenses. Keeping accurate records throughout the year helps ensure you're not paying more tax than necessary.
10. Do I have to mail my estimated tax payments to the IRS?
No. Most self-employed individuals pay electronically using IRS Direct Pay or the Electronic Federal Tax Payment System (EFTPS). These options are secure, convenient, and provide confirmation that your payment was received.
11. Should I use the Safe Harbor Rule or calculate my taxes each quarter?
It depends on your situation. If your income is relatively stable, calculating your taxes based on current income may work well. If your income varies significantly from year to year, the Safe Harbor Rule can provide a simpler way to avoid underpayment penalties.
12. Should I work with a CPA for quarterly estimated taxes?
Many freelancers can estimate their own payments using general guidelines, but a CPA can help you project your tax liability more accurately, maximize deductions, evaluate Safe Harbor strategies, and avoid costly surprises at tax time. For growing businesses or fluctuating income, professional guidance can often save more than it costs.
Quick Summary
Question | Answer |
Who pays? | Self-employed workers who expect to owe $1,000+ in federal taxes |
Due dates | April 15 · June 15 · September 15 · January 15 |
What you owe | Self-employment tax (~14.1% effective) + federal income tax |
Simple approach | Save 25–30% of every payment into a separate account |
Avoid penalties | Pay 100% of last year's tax bill (110% if income over $150K) |
How to pay | IRS Direct Pay (federal) · Your state's tax website (state) |
Key Takeaways
Most freelancers need to make quarterly estimated tax payments if they expect to owe at least $1,000 in federal taxes after withholding and credits.
Quarterly payments cover both federal income tax and self-employment tax, so it's important to plan for both throughout the year.
A simple way to stay prepared is to set aside 25–30% of your net income into a separate tax savings account whenever you get paid.
The Safe Harbor Rule can help you avoid IRS underpayment penalties even if your income changes during the year.
Arizona estimated tax payments are separate from federal payments, so don't forget to account for your state tax obligations if they apply.
Keeping accurate bookkeeping records throughout the year makes estimating taxes much easier and helps ensure you claim every deduction you're entitled to.
Paying quarterly taxes doesn't have to be complicated. With a simple system and regular reviews, you can avoid surprises, reduce stress, and stay in control of your tax obligations.
Quarterly taxes are totally manageable once you understand the system and build the right habits. The goal isn't perfection — it's staying current throughout the year so there are no big, scary surprises in April.
About the Author
Vani Murthy, CPA is the Founder and President of AZ Edge Accounting LLC located in Mesa, Arizona. Since 2008, she has helped small business owners achieve financial success through accurate bookkeeping, proactive tax planning, and strategic tax preparation. After founding AZ Edge Accounting LLC in 2019, Vani has focused on serving Arizona businesses and clients nationwide with personalized guidance and practical accounting solutions.
Vani specializes in helping entrepreneurs maintain accurate financial records, optimize cash flow, prepare simple to complex individual and business tax returns, and develop proactive tax strategies that legally minimize taxes. Her mission is to help business owners keep more of what they earn, build long-term wealth, and gain the financial confidence to grow their businesses.
Disclaimer
This article is provided for informational purposes only and should not be considered tax, legal, or financial advice. Tax laws change frequently and individual circumstances vary. Consult a qualified tax professional regarding your specific situation.
© 2026 Vani Murthy. All rights reserved.
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