Last year I had large itemized deductions by piling enough stuff in there to skip the standard deduction. That led to a significant refund.

I decided to apply it all to estimated tax, because I already pay a notable amount of estimated tax quarterly, having no wage income for withholding. Then I didn't have to worry about cash in my checking account quarterly.

The IRS has twice mailed me saying they are still studying my return, and don't ask.

Now I struggle with what estimated tax to pay quarterly, because I don't know what the result will be with my "apply to next year's taxes" refund.