If you’ve ever filed a personal tax return as an employee, you’ve never actually had to think about quarterly taxes, your employer was withholding them from every paycheck. The first time you go self-employed or run a small business, that mechanism disappears, and the IRS expects you to send them money four times a year on a schedule. Miss the schedule, and you’ll owe penalties on top of the tax itself.
Here’s the plain-English version.
Who has to pay quarterly
The general rule: if you expect to owe at least $1,000 in federal income tax for the year after subtracting your withholding and refundable credits, you’re supposed to be making quarterly estimated payments. That covers most self-employed people, sole proprietors, single-member LLC owners, partners in a partnership, and S-corp shareholders who take distributions. If you also have a W-2 job, the withholding from that paycheck counts — sometimes it’s enough to cover everything and you don’t need to send quarterly payments at all.
The four deadlines
For 2026, the federal quarterly deadlines are:
- Q1: April 15
- Q2: June 15
- Q3: September 15
- Q4: January 15 of the following year
Don’t let the names fool you, these aren’t even quarters. Q1 covers Jan-Mar, Q2 covers April and May only (two months), Q3 covers June-Aug, and Q4 covers Sept-Dec.
How much to send
There are two safe-harbor rules that protect you from underpayment penalties:
- Pay at least 100% of last year’s total tax (110% if your AGI was over $150,000), spread evenly across the four quarters. This is the simplest rule because you already know last year’s number.
- Pay at least 90% of this year’s actual tax liability. This requires estimating your income for the year, harder, but useful if your income drops significantly versus last year.
Most small business owners just pick the easier rule (100/110% of last year) and use that. If income explodes upward, you can adjust mid-year.
The single most useful habit: open a separate “tax” savings account and move 25–30% of every payment you receive into it the day it lands.
State taxes too
If your state has income tax, you usually have to make quarterly estimates there as well. The deadlines often (but not always) match the federal schedule. Washington State has no income tax, so this isn’t a worry for most of my clients, but if you sell in or have nexus in other states, check the rules where your customers are.
The biggest mistake
The biggest mistake I see is owners who pay themselves the gross from every invoice and don’t set anything aside for taxes. Then April rolls around and they owe $15,000 they don’t have. Open a dedicated tax savings account, move 25–30% of every payment into it the day you get paid, and treat that money like it’s not yours, because it isn’t. When quarterly deadlines come, the money is already sitting there waiting.
If you’d like help figuring out the right quarterly amount for your specific situation, that’s part of what good bookkeeping makes easy. Let’s set up a call and talk through it.