IRS: Pay Federal Income Tax Click here to pay your federal income taxes. IRS: Payment Plan Application Click here for the IRS Installment Agreement Request Form. IRS: Payment Plan Instructions Click here for the IRS Installment Agreement Instructions. MO: Pay MO Tax Click here to pay your individual MO state taxes. STL: Pay STL County Tax Click here to look up and pay your STL County taxes. STL: Pay STL City Tax Click here to look up and pay your STL City taxes. IRS: Where's My Refund Click here to see if your Federal return has been processed with the IRS. MO: Where's My Refund Click here to see if your Missouri return has been processed with the state. Ill: Where's My Refund Click here to see if your Illinois return has been processed with the state. MO: Secretary of State Click here to open a MO business. Obtain LLC, Articles of Organization, and other state business docs. Small Business Federal EIN Application Click here to learn about and apply for a federal EIN number. FinCEN's BOI Report Click here to learn about and file your business’s required Beneficial Ownership Information report. Online IRS Identity Theft Affidavit Click here to submit an online Identity Theft Affidavit to the IRS.