Quarterly Tax Deadlines 2026: Don't Miss June 15

Quarterly Tax Deadlines 2026: Do Not Miss June 15

I was driving Olivia to soccer practice last Tuesday when my phone buzzed. A client text: "Michael, when is the next quarterly payment due?" I nearly swerved. It was May 28. The June 15 deadline was eighteen days away. And he had not started calculating his Q2 payment.

This happens every quarter. Every. Single. Quarter. I have been a CPA for eight years and an IRS agent for twelve before that. I have seen penalties stack up like cordwood because people simply forget the dates. So here is your 2026 quarterly tax calendar. Print it. Tape it to your monitor. Set phone reminders. Whatever it takes.

The 2026 Quarterly Schedule

Q1: April 15, 2026 — Covers income January 1 through March 31. This one aligns with the annual filing deadline, which confuses people. Yes, you file your 2025 return AND pay Q1 2026 on the same day.

Q2: June 15, 2026 — Covers income April 1 through May 31. This is the sneaky one. Only two months of income, but the payment is due mid-June. Most people forget because it feels too soon after April.

Q3: September 15, 2026 — Covers income June 1 through August 31. Three months. More time to calculate. But also more time to procrastinate.

Q4: January 15, 2027 — Covers income September 1 through December 31. Due the year AFTER the tax year ends. Confusing, but that is the rule.

How Much Should You Pay?

The safe harbor rules are your friend. Meet any ONE of these, and you avoid penalties:

Pay 90% of your current year tax liability. Pay 100% of your prior year tax liability (110% if your prior year AGI was over $150,000). Pay at least as much through withholding as your prior year liability.

I recommend the 100%/110% rule for most clients. Why? Because it is based on KNOWN numbers (last year's return), not ESTIMATES of this year's income. If you have a booming year, you might owe more in April, but no penalties. If you have a down year, you overpaid and get a refund.

A freelance consultant client of mine made $140,000 in 2025. His total tax: $28,400. For 2026, we set quarterly payments at $7,100 each ($28,400 / 4). Simple. Safe. No penalties. He made $160,000 in 2026. Owed an extra $4,200 in April. But no penalties. Worth it.

The June 15 Trap

Here is why June 15 kills people. After the April 15 rush—filing last year's return, paying Q1—people relax. "I just paid taxes," they think. "I am good for months." Then June arrives, summer vacations start, kids get out of school, and the deadline sneaks up.

I had a real estate agent client miss June 15 three years in a row. Penalties: $1,200, $1,800, $2,100. "I always forget," he admitted. We set up automatic ACH transfers from his business account on June 1, September 1, and January 1. April is manual because the amount depends on his annual filing. Problem solved.

How to Pay

Online: IRS Direct Pay (bank transfer, free), EFTPS (Electronic Federal Tax Payment System, free), or credit card (fees apply, 1.87-1.99%).

By mail: Form 1040-ES voucher with check. Must be postmarked by the deadline.

Estimated: I do not recommend this. Mail gets lost. Checks get delayed. Online is instant and traceable.

State payments: Most states follow federal deadlines, but not all. Texas has no state income tax (one of many reasons I live here). California follows federal. New York is slightly different. Check your state.

What If Your Income Is Uneven?

Freelancers do not earn evenly. You might make $5,000 in January, $25,000 in March, $8,000 in April. The annualized income installment method lets you match payments to actual quarterly income. It is complex—Form 2210, Schedule AI—but can save penalties if your income is front-loaded.

I use this for seasonal businesses. A landscape designer client makes 70% of income March through May. We annualize her installments so Q1 and Q2 are higher, Q3 and Q4 lower. Saves her from overpaying early in the year when cash is tight.

Penalties: The Math of Pain

The IRS underpayment penalty is essentially interest on what you should have paid. The rate is the federal short-term rate plus 3%. For 2026, that is roughly 7-8%. Calculated daily from each quarterly due date until paid.

Miss Q2 by one month? Penalty on that quarter's underpayment for 30 days at 7.5%. Miss it by six months? 180 days of penalty. It adds up. A $3,000 underpayment missed by four months costs about $75 in penalty. Not catastrophic, but completely avoidable.

Farm and Fisherman Exception

If you earn at least two-thirds of income from farming or fishing, you only need ONE estimated payment by January 15, or file by March 1 and pay in full. Special rules for special industries. I do not get many fishermen in Austin, but I have a couple ranch clients who qualify.

The Cooper Rule

I named this after my dog because it is simple: if Cooper can remember his dinner time (5:30 PM, every day, without fail), you can remember four tax dates. Set calendar reminders. Set phone alarms. Tell your spouse. Do whatever it takes.

The IRS does not care that you forgot. They care that you paid late. And they will charge you for the privilege of their patience.

— Michael Harrison
CPA, Former IRS Agent | Austin

The Annualized Income Method: For Uneven Earners

I mentioned this briefly, but it deserves more detail. If your income is not evenly distributed—seasonal business, commission sales, bonus-heavy compensation—the annualized income installment method (Form 2210, Schedule AI) can save significant penalties.

Here is how it works. Instead of paying 25% of your annual estimated tax each quarter, you calculate your actual income and deductions for each period, annualize it, and pay based on that annualized amount.

Example: A real estate agent earns:
Q1 (Jan-Mar): $8,000
Q2 (Apr-May): $35,000
Q3 (Jun-Aug): $12,000
Q4 (Sep-Dec): $25,000
Total: $80,000

Regular method: $20,000 estimated tax / 4 = $5,000 per quarter.
Annualized method:
Q1: $8,000 x 4 = $32,000 annualized. Tax: $3,200. Payment due: $3,200.
Q2: ($8,000 + $35,000) x 2.4 = $103,200 annualized. Cumulative tax: $12,400. Payment due: $12,400 - $3,200 = $9,200.
Q3: ($8,000 + $35,000 + $12,000) x 1.5 = $82,500 annualized. Cumulative tax: $9,200. Payment due: $9,200 - $12,400 = $0 (already overpaid).
Q4: Full year. True-up in April.

Under regular method, Q2 payment is $5,000. But she actually earned $35,000 in Q2. She should have paid $9,200. Underpayment penalty on $4,200 difference.

Under annualized method, she pays what she actually owes when she earns it. No penalty.

The catch? It is complex. You need to track income and deductions by quarter. You need to calculate annualization factors (4x for Q1, 2.4x for Q2, 1.5x for Q3, 1x for Q4). You need to file Form 2210 with your return. Most tax software handles it, but you need accurate quarterly data.

I charge $600-800 to prepare annualized installments for clients. Worth it if it saves $500+ in penalties. Not worth it for steady earners who can just pay evenly.

The "Prior Year Safe Harbor" for New Businesses

What if you started your business mid-year? You have no prior year tax to use for 100% safe harbor. You must use 90% current year. But you do not know your full year income yet.

Strategy: Estimate conservatively. Pay based on a low estimate. If income exceeds estimates, you will owe in April but avoid penalties (since you paid 90% of a conservative estimate, which might be 70% of actual—still, penalties are based on quarterly timing, not just annual total).

Better strategy: Use the annualized method from the start. Pay based on actual quarterly income. No guessing. No underpayment surprises.

I had a client start a consulting business in March 2025. He estimated $60,000 annual income. Paid quarterly estimates of $3,000 each (based on $12,000 annual tax). Actual income: $95,000. Actual tax: $22,000. He paid $12,000 in estimates. Underpaid by $10,000. Penalties: $380.

If he had used annualized method: Q1 (Mar only): $8,000 income. Payment: $800. Q2 (Apr-May): $22,000. Cumulative payment: $3,800. Q3: $18,000. Cumulative: $7,200. Q4: $47,000. Cumulative: $14,000. True-up in April: $8,000. Penalties: $0.

The $380 penalty was not catastrophic. But it was avoidable. And it annoyed him. "I thought I was being conservative," he said. Conservative estimates do not help if your income exceeds them.

State Estimated Taxes: The Hidden Complexity

I mentioned state variations, but let me expand. California follows federal safe harbor rules but adds its own twist: no annualized income method for non-farmers. If your California income is uneven, you cannot use annualized installments. You must pay evenly or face penalties.

New York follows federal rules but has different thresholds. The 110% rule applies at $150,000 NY AGI, not federal AGI. If your federal AGI is $140,000 but NY AGI is $160,000 (due to different add-backs), you need 110% of prior year NY tax.

Texas, Florida, Tennessee, Nevada, Washington, Wyoming, South Dakota: no state income tax. No state estimates. Simple.

I have a client who lives in Austin (Texas, no state tax) but works remotely for a New York company. New York claims taxing rights under the convenience of the employer rule. He pays NY estimated taxes quarterly. He also pays federal quarterly. Two sets of estimates. Two sets of deadlines (mostly aligned, but not always). Two sets of rules.

"I moved to Texas to simplify my taxes," he told me. "It got more complicated." I sympathize. Remote work has created a tax complexity nightmare that states are only beginning to address.

The Self-Employment Tax Quarterly Trap

Self-employment tax (15.3% on 92.35% of net earnings) is part of your total tax liability for estimated payment purposes. Many freelancers calculate their income tax but forget SE tax. Huge mistake.

Example: $80,000 net freelance income. Income tax: roughly $12,000 (after standard deduction). SE tax: $80,000 x 92.35% x 15.3% = $11,304. Total tax: $23,304. Quarterly payments: $5,826.

If you only calculated income tax, you would pay $3,000 per quarter. Underpaid by $2,826 per quarter. Penalties: roughly $340. "I did not know about self-employment tax," the client said. Now he does. Now you do.

The Cooper Rule Revisited

I named my quarterly reminder system after Cooper because it is simple and reliable. Every January, I send clients a calendar with four red-circle dates: April 15, June 15, September 15, January 15. Every quarter, I send an email reminder two weeks before the deadline. One week before, I send another. Three days before, a final nudge.

Some clients find this annoying. "I know the dates, Michael," they say. Then they miss June 15. Every. Single. Year.

The clients who appreciate the reminders never miss a payment. The clients who find them annoying miss 30% of deadlines. Correlation? Causation? I do not care. The reminders work.

Set your own system. Calendar alerts. Phone alarms. Spouse reminders. Automatic bank transfers. Whatever works for you. The IRS does not care about your system. They care about your payment arriving on time.

And if you do miss a deadline? Pay as soon as you realize it. The penalty is calculated daily. Every day you delay costs money. A $5,000 underpayment paid one month late costs roughly $32 in penalty. Paid six months late: $190. Paid immediately: $0 (if you catch it within days and the IRS has not assessed yet).

I had a client miss June 15 by three days. He mailed the check June 18. Postmark: June 18. Penalty assessed: $12. "That is annoying," he said. Yes. Yes, it is. Set reminders. Avoid annoyance.

— Michael Harrison
CPA, Former IRS Agent | Austin