Many corporations have a December year-end and that year-end is coming up soon. If your corporation is having a great year, then more taxes are going to have to be paid for this year than were last year.
A corporation is supposed to be paying monthly installments of income tax. These installments are based on the amount of income that was earned in a prior year. The way the rules work is that you pay your installments during the year, each month, and then any amount owing that exceeds the installments that have been paid is due within three months of year-end. If you are making more money than you made last year, the monthly installments will not be enough, and you will owe more money when the return is calculated.
So, if you are having a great year, understand that you are likely not paying enough in your monthly installments to take care of the taxes that you are going to owe.