IRS Publications - Payroll Tax
Circular E - Employer's Tax Guide
Employer's Supplemental Tax Guide
Circular A - Agricultural Employer's Tax Guide
Reporting Back Pay to the Social Security Administration
Reporting Tip Income
Tax Withholding and Estimated Tax
Employment Taxes for Household Employers
Circular SS - Federal Tax Guide for Employers in the Virgin Islands, Guam, American Samoa, etc.