About EUS
The CMS External User Services (EUS) e-service site is a dedicated on-line resource providing support for Medicare Providers using the PECOS and IACS systems. The External User Services e-service site provides information on the PECOS and IACS systems and the applications they support, including answers to Frequently Asked Questions and links to other helpful resources.
External User Services is the primary help resource for the PECOS and IACS Medicare Provider communities. In addition to the e-service website, External User Services provides a dedicated help desk, which can be reached by phone, by e-mail, or by mail.
Please contact EUS for questions regarding:
- PECOS and IACS access issues.
- Authorized Official or Security Official questions.
- Security Consent Form questions.
If you have policy related questions please contact your Medicare Contractor. If you have questions regarding your NPI please contact the Enumerator help desk. Select the link Additional Support to obtain e-mail addresses and phone numbers for those help desks.
Contact Us
By Phone
Toll-Free:(866) 484-8049, (866) 523-4759 (TTY/TDD)
Outside the Continental US:(210) 918-1083
Hours: Monday - Friday, 7am-7pm EST
By E-mail:
By Mail:
CMS External User Services
PO Box 792750
San Antonio, Texas 78279
* please note the USPS recently changed our zipcode from 78216 to 78279
