In general, you should wait at least 2-4 weeks if you filed electronically, and 6-10 weeks for a paper filing before contacting the tax authorities. Be sure to have a copy of your tax return in front of you before calling.
Automated Refund Hotline: 1-800-829-1954
For any other inquiry, call 1-800-829-1040, 7am - 7pm.
Outside the U.S., call (267) 941-1000
New York State (Forms IT-201 or IT-203):
Automated Refund Hotline: 518-457-5149
Other inquires: 518-457-5181
New Jersey (Forms NJ-1040 & NJ-1040NR):
To speak to a live person, call 1-609-292-6400, 8:30am-4:30pm, Monday-Friday.
California (Form 540 & 540NR):
Customer Service: 1-800-852-5711
Many other states have links to check a refund status online. Please see my Links page for a complete list of State Tax Websites.