You may mail this form to TRS at:
Teachers’ Retirement System
PO Box 19253
Springfield IL 62794-9253
Or you may fax it to: (217) 753-0964.
Go to http://www.irs.gov/pub/irs-pdf/fw4p.pdf to download the IRS long form (4-pages) W-4P Withholding Certificate for Pension or Annuity Payments.
Or you may download TRS's short version of the W-4P (1 page).