Most businesses should have completed a Kentucky Department of Revenue Tax Registration Application in Step 2 of the Start page on Kentucky Business One Stop. DOR has created a withholding tax calculator to assist employers in computing the correct amount of Kentucky withholding tax for employees.Pay all business taxes including sales and use, employer withholding, corporate income, and other miscellaneous taxes. Using Form W-4 to figure withholding. Electronic system to receive Form W-4. Review the below options carefully to select the correct form for the date of sale. Using the wrong form may cause the tax to be calculated incorrectly. I'm a bit new to accounting and manager. Io in general but I was wondering how withholding tax gets counted when invoicing customers. If the withholding tax filing or deposit due date falls on a holiday, the due date is extended to the next business day.