Definitely it is indeed very confusing because the visa stamp functions effectively like a plane ticket. The non immigrant needs that valid visa stamp in order to enter the US. It is only a travel document that only needs to be valid on the day of admission to the US except of course of traveling under automatic visa revalidation as just discussed. The i 94 document on the other hand is what controls the category and authorized stay in the United States. Therefore, while a visa stamp can expire after entry to the US, the I 94 needs to remain valid at all times. The I 94 can be issued in one of two ways on entry to the US by US Customs and Border Protection or CBP. And through US Citizenship and Immigration Services or USCIS at the bottom of an ice 797 approval notice. The exception is that the approval is for consular notification in that case the approval will not have the detachable I 94 at the bottom. The last issued i 94 is the one that controls the status. Therefore, it is important to download and check the I 94 from the CBP website after each admission to the US. Even if the I 94 issued by USCIS on an approval notice is still valid.Travelers should confirm that the status listed is correct and that the expiration date is correct. The expiration date can be cut short due to an error for instance, the officer may issue the validity of the I 94 until the visa expiration date which is not correct or they may limit the I 94 validity to the passport expiration date which would be correct. Errors can be corrected, but being cut short because of a passport expiration cannot be corrected. Therefore passport should be renewed well in advance to avoid this issue. overstaying an I-94 can have very serious consequences.