The IRS has a website, at http://www.irs.treas.gov/ that provides income tax forms, publications, and other resources for taxpayers. Some publications that may be of interest to a postdoc are:

Publication 1: Your Rights as a Taxpayer

Publication 15: Circular E, Employer's Tax Guide: This guide can be used to determine the amount of tax to be withheld on salaries.

Publication 513: Tax Information for Visitors to the U.S.- An overview of the U.S. tax system and regulations applicable to foreign nationals.

Publication 515: Withholding of Tax on Nonresident Aliens and Foreign Nationals.

Publication 519: U.S. Tax Guide for Aliens-Includes information on how to determine residence or nonresidence status for tax purposes; what kinds of income are taxed; the effect of tax treaties on tax oliability; how to claim exemption by treaty, etc.

Topic 421- Scholarship and Fellowship Grants

Publication 525: Taxable and Nontaxable Income

Publication 901: U.S. Tax Treaties- All treaties in effect at the time of publication, with summaries of articles relating to students and scholars.