I expect to make a home purchase perhaps, probably

I expect to make a home purchase perhaps, probably not a million, but a large capital gain.  $20 by end of May is possible, and removing my basis will require a quarterly tax payment.  Believe me - 90% of my holdings are in it until at least $51.53.

Do you know the form or pub number that I search for on IRS.gov to make the payment?  More of a curiosity at this point.  I know May is a few months away, but I have  been diagnosed with PFPOCD (Personal Financial Planning Obsessive Compulsive Disorder)