Paying estimated taxes on a W2 job - Is it okay to under-withold and make it up with a quarterly payment?

Question

Filling out W4's becomes tricky when there are multiple jobs, and more so when the jobs have very different wages, or are bursty. Is there anything wrong with having the withholdings be low, and then paying estimated taxes each quarter?

Details:

One spouse has the main wage-earning job (over 90% of income) and it fluctuates a little bit. Its W4 is fine. The other spouse has a very part-time job that pays anywhere from $0 to $1000 a month. The W4 for the part-time job was hastily filled out in a way that basically results in no withholdings.

As I understand it, the recommended path here is to have the small second job have a fixed withholding taken out every month (Federal W4, step 2 option (b)). However, it is hard to know ahead of time what to put there because the income is so inconsistent.

Is there anything wrong with leaving the W4 as it is and just paying estimated taxes each quarter? (Basically filing estimated taxes like the second job was a 1099) That way there is no need to predict what the income will be on the W4. (This would be for both Federal and Oregon State taxes).

For example

If in April through May the second job payed $500, and the yearly income is projected to reach to the 22% tax bracket, then Q2 federal estimated taxes could be payed as 22% * $500.

Answer 1

Besides the use of the 4 estimated payments option, you can setup the w-4 form for the main income to guarantee that you make the safe-harbor levels of withholding.

The issue for your family is that one income is large and reasonably steady, but the other can range from $0 to $1000 in a month. That means that the advice of a fixed amount of withholding on the 2nd income is hard to do. My family was in the same situation many years ago.

One way to be able to avoid having to pay a penalty for underpayment or under-withholding is to then adjust the main W-4 to make the safe harbor.

General Rule

In most cases, you must pay estimated tax for 2023 if both of the following apply.

1. You expect to owe at least $1,000 in tax for 2023 after subtracting your withholding and tax credits.

2. You expect your withholding and tax credits to be less than the smaller of:

• 90% of the tax to be shown on your 2023 tax return, or

• 100% of the tax shown on your 2022 tax return. Your 2022 tax return must cover all 12 months.

Note. The percentages in (2a) or (2b) just listed may be different if you are a farmer, fisherman, or higher income taxpayer. See Special Rules, later.

Higher Income Taxpayers

If your AGI for 2022 was more than $150,000 ($75,000 if your filing status for 2023 is married filing a separate return), substitute 110% for 100% in (2b) under General Rule, earlier.

For 2022, AGI is the amount shown on Form 1040 or 1040-SR, line 11.

The risk in this method is that you might have too much money withheld if the AGI for 2023 is lower than the AGI for 2022. A benefit of this method is you do know that you will avoid the underpayment penalty.

Answer 2

In this situation, I don't see that as a problem. Yes, the W-4 has the whole "Under penalties of perjury..." section, but I haven't heard of a time when anyone got in trouble for their W-4.

If the main job has withholding as if it's the only job, your approach of estimating taxes for the 2nd job based on your marginal bracket makes sense, and it should work. It's easiest if the additional income is relatively small and doesn't push into another tax bracket (especially if it's 12% to 22% or 24% to 32%), but it can still work across tax brackets. Just a bit more math.

You may want to double-check with the IRS' tax withholding estimator tool periodically. For whatever reason, the new W-4 forms (since 2020) seem to be notoriously troublesome for taxpayers.