The USCIS will resume premium processing of phase-one cases by no later than May 27, 2020, and will notify the public before premium processing resumes for these cases. The soonest the USCIS will resume premium processing for phase-two cases is June 29, 2020. Until premium processing resumes, the USCIS will reject any request for premium processing (form I-907) filed for a cap-subject H1B petition.
Note that the suspension of premium processing only applies to cap-subject petitions. Premium processing remains available for all other H1B petitions.
Murthy LF, 16 March 2020