When a corporation files Form 2553 with the Internal Revenue Service to elect to be treated for tax purposes as an S corporation, the IRS makes a determination regarding the corporation's eligibility for the designation, and returns a letter approving or denying the election. If the election is approved, the letter also indicates the tax year the election became effective, which is particularly important for tax filing purposes. This letter should become part of the corporation's records. If it is misplaced, request a copy from the IRS.

Call the Internal Revenue Service's Business and Specialty Tax Line. This is the department a corporation calls to obtain a copy of almost any letter from the IRS regarding business matters, including Subchapter S elections and Employer Identification Number assignments. The phone number is 800-829-4933. As of October 2010, the hours of operation are 7 a.m. to 10 p.m., Monday through Friday.

Request a copy of the corporation's S corporation determination letter. The IRS representative will ask for identifying information and the corporation's EIN. As long as you are a person who is authorized to transact business on behalf of the corporation (for example, a corporate officer), the representative will send a copy of the letter to the corporation by mail. Sometimes, the representative can send a copy of the letter via fax, but that sort of service depends on how busy the office is at the time of your call.

Add the duplicate letter to the corporation's records when it arrives. Check to make sure that the information reflected in the letter comports with memory and practice. If you find any discrepancies, contact the IRS for guidance.