The 12 and 24 month rule affects J-1 exchange visitors who have been in the U.S. on a J-1 visa previously, and wish to return, using the J-1 visa. In essence, the 12-month and 24-month bars limit how quickly a person can "play the J-1 game" in succession. The bars create built-in pauses during which the scholar is not eligible to return to the US in J status. This, again, encourages the scholar to remain abroad to transfer the skills and knowledge they acquired in the USA to their colleagues in their home country. 

The bars prohibit certain “repeat participation” in the Research Scholar or Professor categories only. Depending on what your previous J category was, you may be subject to a 12 month bar, a 24 month bar or have no bar at all.

Note that the 24-month bar to repeat J participation is different from the J-1 2-year home residence role. Although both are for the same amoun of time (730 days), there are completely different purposes and consequences to each rule.

 

Below is a chart that shows whether a 12-month or 24-month bar might arise. The J categories in the column on the far left (in red) are the possible J visa cateogies you might have held in the past.  The row headers in blue show the J program you are now interested in seeking sponsorship for. 

The J-2 dependent is subject to the same bar as the J-1. In other words, if you previously were the J-2 of a J-1 Short-Term Scholar, you would begin by looking to the red J-1 Short-Term Scholar category cell on the far left. If you or your family member wants to pursue a future J-1 Short-Term Scholar visit, then you would look to the (blue) J-1 Short-Term Scholar cell. 

Prior Visit Less than 6 Months

If you have held the visa classification in red for any time at all (even as little as one day), up to but less than 6 months, and you want to pursue one of the J visa classes in blue...

J-1 Student Degree / Non-Degree J-1 Student Intern J-1 Short-Term Scholar J-1 Specialist J-1 Research Scholar
J-1 Student Non-Degree / Degree  (no comment) No bar No bar No bar No bar
J-1 Student Intern No bar No bar No bar No bar
J-1 Short-Term Scholar No bar No bar No bar
J-1 Specialist No bar No bar No bar
J-1 Research Scholar / Professor No bar 24-month bar

 

Prior Visit 6 Months or More

 If you have held the visa classification in red for 6 months or more, and you want to pursue one of the J visa classes in blue...

J-1 Student Degree / Non-Degree J-1 Student Intern J-1 Short-Term Scholar J-1 Specialist J-1 Research Scholar
J-1 Student Non-Degree  (no comment) No bar No bar No bar 12-month bar
J-1 Student Intern No bar No bar No bar 12-month bar
J-1 Short-Term Scholar No bar No bar 12-month bar
J-1 Specialist No bar No bar 12-month bar
J-1 Research Scholar / Professor No bar 24-month bar