From uscis.gov on 11/29/18: USCIS has published a policy memorandum (PDF, 121 KB) (PM) clarifying the requirement that a qualifying organization employ a principal L-1 visa beneficiary abroad for one continuous year out of the three years before the time of petition filing (“one-year foreign employment requirement”).
This clarification is intended to ensure consistent adjudication of L-1 petitions by providing a standard basis for calculating time for the one-year foreign employment requirement.
The L-1 nonimmigrant classification allows a U.S. employer to transfer an executive or manager (L-1A) or an employee with specialized knowledge (L-1B) from one of its qualifying foreign offices to one of its offices in the United States.
This classification allows a foreign company that does not yet have a qualifying U.S. office to send an executive or manager, or specialized knowledge employee, to the United States to establish one.
Specifically, this PM explains that:
Except as noted in the PM, the one year of foreign employment must occur within the three-year period preceding the date the L-1 petition is filed. USCIS will calculate the three-year period during which the beneficiary must meet the one-year foreign employment requirement.
The PM also clarifies what time will be taken into consideration in determining when the three-year period begins.
In support of the Buy American and Hire American Executive Order, USCIS is reviewing all employment-based immigration programs to eliminate fraud and ensure consistent adjudications.
USCIS has not previously provided specific policy guidance with respect to the conditions by which the three-year clock may be stopped for purposes of determining whether the one-year foreign employment requirement for L-1 beneficiaries has been met.
This PM improves the process for adjudicating the L-1 nonimmigrant benefit by clarifying the calculation guidelines to ensure they are applied consistently to all L-1 petitions.
Source: h1b now