Registration
While inside the United States, international students and scholars and dependents should carry a document that demonstrates their evidence of registration.
Is this a new requirement? No. See INA 264 [8 USC 1304].
What is registration? International students and scholars and dependents are registered when they apply for a visa (see INA 221(b) [8 USC 1201(b)]), and when they are admitted into the United States and issued a Form I-94 INA 262 [8 USC 1302]. A registration is updated when an extension of stay or a change of status is approved.
What documents can I use as evidence of registration? International students and scholars and dependents will usually have a Form I-94 or an EAD card. See 8 CFR Part 264. If you choose to carry an Form I-94, you will need to print a hard copy of an electronic Form I-94 to satisfy this requirement. See 8 CFR 1.4(f). A foreign passport with an admission stamp is also evidence of registration. However, since most international students and scholars and dependents are admitted to the United States without an admission stamp and carrying a passport daily may increase the possibility of it getting lost, we do not recommend that you carry your passports as evidence of registration. It could be helpful to also carry an electronic I-20, DS-2019, or I-797 approval notice to further demonstrate your nonimmigrant status.
U.S. permanent residents. While U.S. permanent residents are not international students or scholars, as non-U.S. citizens, they also required to be registered and to carry documentation to demonstrate compliance while inside the United States. Specifically, U.S. permanent residents may carry their I-551 Permanent Resident Card to demonstrate their registration.
Other documents
F-1 students should "carry" an I-20 with them. This is distinct from the requirement to have documents to demonstrate registration, as described above. Since the I-20 may be transmitted electronically, an electronic copy should be sufficient to meet this obligation. Specifically, the I-20 instructions state, "The Form I-20 (this form) is the primary document to show that you have been admitted to school in the United States and that you are authorized to apply for admission to the United States in F-1 class of admission. You must have your Form I-20 with you at all times. If you lose your Form I-20, you must request a new one from your designated school official (DSO) at the school named on your Form I-20."
Other Types of ID
California ID is a government-issued ID that is available for people in California who do not drive. See the DMV website. International students or scholars may find it useful to have a U.S.-issued ID instead of carrying a passport.
Real ID will go into effect on May 7, 2025. Real ID will require all individuals to have a REAL ID-compliant identification document to enter federal facilities, board commercial aircraft, enter nuclear power plants, and for "any other purposes that the Secretary [of Homeland Security] shall determine." Washington State's enhanced driver's licenses and identification cards are an acceptable alternative to a REAL ID. A foreign passport is a REAL-ID compliant document.