TAX SHELTERED ANNUITY OPTION. A retiring employee shall be permitted to place a portion of his or her severance pay to a tax-sheltered annuity, provided that the election to defer is made prior to the date that the board of education accepts the employee’s resignation. The election to defer severance pay is irrevocable after the board accepts the resignation. The deferral to a tax sheltered annuity must follow the guidelines of the Internal Revenue Code, IRC Section 15 (C) (4) (B). The tax sheltered annuity company must provide the Treasurer of the school district their calculations showing that the amount to be deferred does, indeed, comply with the I.R.C. regulations.