Filling out government forms is never a walk in the park, and mistakes can lead to costs and delays. Confidence in what kind of information your I-90 application is asking for takes a lot of stress out of your submission. Off the tops of our heads, most of us don’t know what our “class of admission” is, so let’s start with that.
Your Class of Admission is asked on Item Number 14 on your Form I-90. Essentially this 3-digit code identifies the category of your lawful residence status. For example, you could be identified as a “Self Petition unmarried son/daughter – of US Citizen – Family Sponsored First Preference” aka B16, or a “Brother or sister of a country-region place U.S. citizen” (F41). There are hundreds of 3-digit codes that correspond with each of these categories, the complete USCIS list can be found here, but the best way to know how you were classified is to look at your Permanent Resident Card under Category. It is typically one or two letters followed by a single number.
To be clear, this states the status under which you were granted permanent residence, not the category that you entered the United States under. If you have more questions about form I-90, check out this article.