Here are a few phone numbers & links that we feel maybe of interest to you:

IRS:   www.irs.gov  800-829-1040 for individuals    800-829-4933 for businesses

California's Franchise Tax Board: www.ftb.ca.gov   800-338-0505

IRS Withholding Calculator: www.irs.gov/individuals/article/0,,id=96196,00.html

Board of Equalization: www.boe.ca.gov   800-400-7115

IRS Tax Forms (many back years):   www.1040.com/FederalLookup.cfm

State Tax Forms (all states with many back years):  www.1040.com/StateLookup.cfm