USCIS looks back 3 years from the date the initial L-1 petition is filed for your L1 eligibility. #1 Find the dates you worked for the employer outside the USA. #2 Find the lengths of any breaks in your employment during the 3 years before the L-1 petition. If you worked for the same employer in the US as an H1B worker earlier, adjust the 3-year period accordingly. An example is given below. #3 Subtract the total length of all the breaks found in Step 2 from the relevant three-year period. If the result is a continuous 1-year period within the relevant 3-year period, then you have met the one-year foreign employment requirement.