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Quarterly Estimated Taxes for Mobile Mechanics: 2026 Due Dates, Safe Harbors, and How Much to Set Aside

Updated 2026-10-17. Sources are listed at the end.

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This is general information, not legal or tax advice. Rules vary by state and change often. Confirm with the official source linked in each section, or with a licensed attorney, CPA or insurance agent, before you act.

The first year on your own is often when a mechanic learns about estimated taxes, usually from an underpayment penalty. No employer is withholding tax from your jobs. The IRS expects you to pay during the year, in four installments. Here are the rules, from the IRS.

Do you have to pay estimated taxes?

Generally yes, if you expect to owe $1,000 or more in tax for the year after subtracting withholding and credits (IRS, Estimated taxes). For a profitable mobile mechanic with no other withholding, that threshold comes fast.

It’s not just income tax. Your net self-employment earnings are also subject to self-employment tax of 15.3%: 12.4% Social Security plus 2.9% Medicare. You have to pay SE tax and file Schedule SE if your net self-employment earnings are $400 or more. You can deduct the employer-equivalent half of SE tax when figuring your adjusted gross income (IRS, Self-employment tax).

2026 due dates

From the 2026 Form 1040-ES:

PaymentFor income earnedDue
1Jan 1 – Mar 31April 15, 2026
2Apr 1 – May 31June 15, 2026
3Jun 1 – Aug 31September 15, 2026
4Sep 1 – Dec 31January 15, 2027

You don’t have to make the January payment if you file your 2026 return by February 1, 2027 and pay the full balance with it (IRS Form 1040-ES (2026), PDF). Note the “quarters” aren’t equal: the second covers only two months.

The safe harbors: how to avoid the penalty

According to the IRS, you generally avoid the underpayment penalty if what you paid during the year (estimates plus any withholding) is at least the smaller of:

(IRS, Estimated taxes; Form 1040-ES)

Why the prior-year rule is useful for a growing business: you know last year’s tax exactly. Divide 100% (or 110%) of it by four and pay that on each due date. Even if this year is much better, you avoid the penalty. You’ll owe the difference in April, so save for it.

How much to set aside from each job

A simple method many solo operators use:

  1. Move a fixed percentage of every payment into a separate tax account, the day it lands.
  2. Choose the percentage from last year’s return: total federal and state tax ÷ net profit. In your first year, estimate with the Form 1040-ES worksheet.
  3. Pay estimates out of that account on the four due dates.

Example (illustration only): if your 2025 return showed $14,000 of total federal tax (income tax plus SE tax) on $60,000 of net profit, that’s about 23% of profit. Set aside about 23% of each job’s profit (not its gross). To meet the 100% prior-year safe harbor, pay $14,000 ÷ 4 = $3,500 per due date.

Your profit depends on your pricing. If the set-aside makes your take-home look thin, check whether your rate covers taxes and overhead with the labor rate & break-even calculator. Its profit line is pre-tax.

How to pay

The IRS lists ways to pay, including IRS Direct Pay (free, from a bank account), EFTPS, your IRS online account, and card payments through approved processors (which charge a fee) (Form 1040-ES; IRS, Estimated taxes). Most states with an income tax have their own estimated payments too. Check your state revenue department.

Lower the bill legitimately

Sources