It's $100K per employee per year.
"the entry into the United States of aliens as nonimmigrants to perform services in a specialty occupation under section 101(a)(15)(H)(i)(b) of the INA, 8 U.S.C. 1101(a)(15)(H)(i)(b), is restricted, except for those aliens whose petitions are accompanied or supplemented by a payment of $100,000"
It sounds like it applies every time you leave and enter, provided you are a nonimmigrant alien on H1B (which they all are).
I do find it interesting that these trillion dollar companies can't find domestic workers, at their level of wealth they should simply be forced to pay for the education of Americans to create a funnel of workers rather than exporting this societal need to other nations.
The Hyundai factory exposed this. The VISA'd employees (or non-VISA'd? I don't remember the details offhand) were only there in the first place overseeing the project because they literally could not find anyone qualified to do the fucking job in Georgia.
Ultimately this isn't going to do anything to reform the H-1B program; this is just trump "doing something", which he'll claim as a success (and his base will eat up), even if it does nothing or makes things worse.