The IRS wants its money four times a year, not once

If you’ve only ever had a W-2 job, tax season is a once-a-year thing. Drive for a living and it’s a four-times-a-year thing, and nobody hands you the schedule.

Why quarterly, specifically

A W-2 employer withholds tax from every paycheck and sends it to the IRS on your behalf, all year, automatically. As a 1099 driver, nobody’s doing that for you — which means the IRS expects you to send in your own estimated payments as you earn, not in one lump sum the following April.

The due dates land roughly in the middle of April, June, September, and the following January — four payments covering the prior income period, not neat calendar quarters. Miss the pattern and you’re not just late once, you can be late four separate times.

What actually happens if you skip it

Nothing dramatic happens the day you miss a quarterly payment — no letter shows up immediately. What happens is quieter: the IRS calculates an underpayment penalty based on how much you owed each quarter and how late you paid it, then adds that penalty to your bill when you file. It’s interest-like, not a flat fine, and it compounds the longer you wait to pay any given quarter.

The safe-harbor number that makes this simple

You don’t have to predict your income perfectly to avoid the penalty. The IRS gives you a safe-harbor rule: pay in, across the year, at least the smaller of two numbers — a percentage of what you expect to owe this year, or a percentage of what you actually owed last year. Hit either threshold through your quarterly payments and the underpayment penalty doesn’t apply, even if your final number ends up higher.

That second option — basing this year’s payments on last year’s bill — is the one most drivers should actually use. It doesn’t require guessing this year’s income at all, just knowing last year’s number and dividing it by four.

TODO — this article should eventually link out to the exact current safe-harbor percentages and due dates once those are sourced from the IRS for the relevant tax year, rather than stating a number here that could go stale. Don’t publish with a specific percentage hardcoded without checking it’s current.