The DMV will accept your registration renewal payment at anytime. The difference is, when you don't have a passing smog check or smog certificate, they will not complete the renewal; they will give you "half-way" papers. You will get a completed registration renewal after your vehicle passes the smog check.
Your vehicles smog check results will be sent to the DMV from the smog station electronically, and the DMV will mail you your vehicle's tags (if all other DMV requirements have been met), or you may visit a DMV field office to pick them up.
posted by SmogTips Support