My questions for other self-employed folks and any tax experts out there: What kind of a penalty would someone be looking at if they didn't pay quarterly at all? Are we talking around or less than $100? Hundreds? Thousands? A percentage of total tax burden?
The current penalty rate (which changes all the time) is 0.0137%
per day, from the time the payment should have been paid until the time it actually is paid. For example, a $5000 payment due on September 15, 2022, but not paid until April 15, 2023 will get a penalty of $145, assuming the penalties don't change. That's just the penalty for that one payment.
That's roughly equivalent to a bank car loan interest. I'm not going to opine on whether this is a legitimate strategy. But if it's between that and a check-cashing store or a credit card advance, I would absolutely take the IRS penalty rate. Make absolutely sure that you have the money ready at tax filing time, or the penalties get a lot worse.
This is complicated by a few other things, which you should be aware of. First, "How much you should have paid" is determined by how much your total tax liability turns out to be, and as you pointed out, you can't know that until you file your taxes.
Second, you have the option to decide at filing time to average your amounts due over each quarter, if that will make your penalty less. Since you said you paid a "massive amount" in the first two quarters, this may be the answer you're looking for. A massive amount of tax due, averaged with two lean quarters may mean that your amounts due are less than you think. Then if you've overpaid for the first two quarters, those overpayments are applied to subsequent payments.
And finally, you are allowed to calculate your penalty based on the tax liability from the previous year. That is, you can ignore this year completely, and pay according to how much you owed last year (110% of that if you were "high income" last year.)
I hope that made sense. You may want to go through the worksheets in the Form 1040-ES instructions. Another option is to get a Form 2210 from last year, and fill it out with hypothetical numbers for this year. If you had a lot of income early in the year, try not using "Box C". (Box C is a pain in the butt anyway).
What about the penalty if someone pays quarterly, but pays less than they owe because they simply can't afford it at the time? Does the IRS look favorably on that? Thanks in advance for any help.
You can get a waiver of the penalty if you were hit by a bus and were in a coma, and weren't able to send in a check. But you don't get a waiver for being unable to pay. In the IRS's view, you had the income, so you must be able to pay.