It shouldn't be that bad because our S Corp was inactive this year but I have learned the hard way to do what I can on our taxes before Dec 31st. One year, when our business was active -- I discovered we had better make a $20,000.00 payment! (I was the corporation's accountant and lacked the necessary training and experience but I got a break from doing any payroll calculations for a while -- that payment to the IRS meant no paydays for a while). When we don't work for ourselves, the "surprise" is never greater than $2000.00. (Sounds preventable, yes, but my H never follows my suggestions when it comes to setting up his W-4 deductions) Hopefully, we will be in for a good surprise this year.....

It is a good practice to run the calculations before the 31st.