ISSS must be notified in advance of change in FTE (Full-Time Employment) whether it be a change from full-time to part-time or viceversa. Because a change in FTE is considered a substantial change in employment conditions, ISSS will be required to file an amended H-1B petition BEFORE the change in FTE may occur. Therefore it is important that the hiring department submit a request to sponsor you for an amendment in your H-1B employment.
You and the department should follow the instructions outlined in requesting an Amendment.
The department should complete a Change in FTE form and compose a letter of notification to ISSS and send it to ISSS.
Since a change in FTE requires the filing of an H-1B petition, you and the department should follow the instructions under amend/extend.