The J-1 program sponsor who issued the original Form IAP-66 (Certificate of Eligibility) may extend your J-1 Status by completing a new IAP-66 with the extended expiration date, provided the date falls within the maximum duration period and notifies the State Department of the change. It is NOT necessary to notify USCIS. This procedure applies only if your J-1 alien's I-94 Form (Departure-Arrival Record) is marked "D/S" or Duration of Status.

Special Extension for J-1 Professors and Research Scholars
J-1 Professors and Research Scholars are eligible to extend their stay for an additional six (6) months after the three-year maximum duration period provided that the extension is necessary in order for the alien to complete a specific project or research program. The granting of the extension falls wholly within the program sponsor's discretion and no State Department or USCIS approval is required.

J-1 Professors and Research Scholars are also eligible to extend their stay via the State Department. The State Department may authorize an extension beyond the three-year period if "exceptional and unusual" circumstances exist. The extension request should be made with Department of State within NINETY days prior to the expiration of the alien's three-year stay period.

For more information about J-1 visa, please refer to the following links:
Description
Work for Non-Sponsor Employer
Duration
Extension
Benefits
Limitations
Procedure to Get a J-1 Visa
J-1 Waiver
No Objection Waiver
Independent Government Agency Waiver
Independent Government Agency Waiver for Physicians
IGA Listing
Exceptional Hardship Waiver
Fear of Persecution Waiver
State Health Agency Waiver (For Physicians only)
State Health Agency Listing
Green Card
Services that We Provide
Frequently Asked Questions about J-1/J-2 Visa
Frequently Asked Questions about J-1 two-year rule
Frequently Asked Questions about J-1 Waiver
Attorney's Fees
Articles & News on J-1