AC21 Portability: When Can Your H-1B Transfer Hire Start Work?

Under AC21 portability, an H-1B beneficiary changing employers may begin working for the new employer upon USCIS receipt of a timely filed change-of-employer petition — not upon approval. This is critical for employers planning start dates, but it comes with conditions and risks if the petition is denied.

Requirements for portability (simplified)

• New employer files a non-frivolous H-1B petition before the candidate's authorized status ends
• Candidate was lawfully admitted and has not worked without authorization
• New petition is for concurrent or subsequent H-1B employment
• Receipt notice (I-797C) issued — employer should confirm before start date

What HR should document

• Copy of filed I-129 and receipt notice in the employee file
• LCA posting and PAF for the new worksite
• Written offer letter with start date after receipt (not before filing)
• Plan if USCIS issues an RFE or denial — counsel should advise

This article is general information, not legal advice. Employers should confirm portability eligibility with immigration counsel for each hire. h1bfiling.com prepares and files change-of-employer petitions with attorney review on every case.