What happened if a man did not register for roman citizenship?

If a man did not register for Roman citizenship, he would remain a non-citizen, often referred to as a "peregrinus." This status limited his legal rights, including the ability to own property, participate in legal proceedings, and vote. Additionally, non-citizens could be subjected to different laws and taxes and lacked the protections and privileges afforded to Roman citizens, such as the right to appeal to the Emperor. In some cases, non-citizens could face social stigma and exclusion from certain civic activities.