My wife and I didn't withhold enough from our salaries for most of the year, and we use the withholding method rather than the estimated taxes method to ensure that we pay enough taxes before the end of the year, so we need to adjust our withholding for the remaining paychecks until the end of the year to make up the difference.
We use TurboTax, which fortunately has functionality for doing this built in. However, after I enter all the numbers and TurboTax spits out new W-4 forms for my wife and me to turn in to our employers, there's a problem: line 4(a) on the forms, the "Other income (not from jobs)" line, is negative.
Neither my employer nor my wife's will accept a negative value for that line. Which makes sense, because how can you have negative income from other jobs? I don't think the IRS intended for there to be a negative value on this line, so I think TurboTax is just completely borked to be doing this. I'd be interested in hearing whether other people agree. Not that it matters, I suppose, because Intuit is notoriously difficult to give feedback to in any way that is likely to reach a human who can do something about it, so even if I think TurboTax is totally wrong here, it's unlikely that I can convince them to change the program to do things differently.
As a workaround, we're taking the negative value from line
4(a) and entering it as a positive value on line 4(b) ("Deductions") in the online W-4 forms provided by our employers. TurtoTax already put a value on that line, so we're just adding the value TurboTax wanted us to put as a negative on line 4(a) to the value already on line 4(b). What do people think about that as a viable workaround?