Tax Guide O 519 U.S. Tax Guide for Aliens U 901 U.S. Tax Treaties Form (and instructions) a SS-4 Application for Employer Identification Number K W-2 Wage and Tax Statement K W-4 Employee's Withholding Allowance Certificate U W-4P Withholding Certificate for Pension or Annuity Payments Page 2 Publication 515 (2011)