| Service | Telephone Number | Hours of Operation |
| Refund Hotline. | 800-829-1954 | Automated service is available 24/7 |
| IRS Help Line for Individuals | 800-829-1040 | M-F 7:00 a.m.-10:00 p.m., local time |
| Business and Specialty Tax Line | 800-829-4933 | M-F 7:00 a.m.-10:00 p.m., local time |
| Forms and Publications | 800-829-3676 | M-F 7:00 a.m.-10:00 p.m., local time |
| Electronic Federal Tax Payment System (EFTPS) | 800-555-4477 | Automated service is available 24/7 |
| TeleTax Topics and Refund Status | 800-829-4477 | Automated service is available 24/7 |
| Employer Identification Number (EIN) | 800-829-4933 | M-F 7:00 a.m.-10:00 p.m., local time |
| Disaster or Combat Zone Hotline | 866-582-5227 | M-F 7:00 a.m.-10:00 p.m., local time |
| Excise Tax and Form 2290 Help Line | 866-699-4096 | M-F 7:00 a.m.-10:00 p.m., local time |
| National Taxpayer Advocate | 877-777-4778 | M-F 8:00 a.m.-6:00 p.m., ET |
| Telephone Device for the Deaf (TDD) | 800-829-4059 | M-F 7:00 a.m.-10:00 p.m., local time |