How to estimate W4 using annual income only with irregular third job

Good morning, everyone.

 

I have a bit of a weird W4 situation, and I'm trying to figure out how to make it work in the IRS's W4 estimator.

 

Between my wife and I, we have three jobs:

1. She works a job with a regular salary (yay, this one's easy for the W4 estimator)

2. I just started a new school job where my salary is prorated for the rest of the school year, but will be at the full salary in the fall. I think the estimator can handle this as well, as long as I get the correct expected income for the whole year in there.

3. I have a third job that I work during school breaks. I can roughly estimate my pay for the year, but the estimator's asking for whether I get paid weekly, biweekly, etc, which I can't really answer because some weeks I'll get paid a few thousand dollars, and some weeks (or months) I'll make nothing.

 

I'm trying to figure out how to fudge these numbers so that I gat a W4 that makes sense, because last year I definitely failed at this and we overpaid our taxes by a five-figure amount, something I'd like to avoid again this year.

 

Can anyone provide any advice?