Q1 Estimated Tax (Form 1040-ES)

What is this deadline?

The first of four quarterly estimated tax payments for US taxpayers with non-withheld income — self-employed individuals, sole proprietors, single-member LLCs, and S-corp shareholders. Covers income earned January 1 through March 31, 2026.

Who needs to file?

Anyone who expects to owe $1,000 or more in federal tax after withholding and credits. In practice, every self-employed person.

Key dates

• Due: April 15, 2026
• Safe harbor: pay the lesser of 90% of current-year tax or 100% of prior-year tax (110% if prior-year AGI > $150K)

How to file

• Pay online at IRS Direct Pay (free, no account needed)
• Or mail Form 1040-ES with a check
• EFTPS works too if you already use it

What people miss

• Safe harbor is calendar-year, not "total paid by April 15." You can underpay Q1 if you catch up by Q4 — but if your income is lumpy, the IRS treats your payments as spread evenly unless you file Form 2210 with the annualised income installment method.
• State estimated tax is a separate deadline (CA, NY, etc.). Easy to miss.
• Self-employment tax counts too — it's ~15.3% of net SE earnings on top of income tax.

If you miss the deadline

Form 2210 penalty (roughly 8% annualised on the underpayment). Not huge but accumulates across the year.