New Resident / Vehicle Registration
New Texas Residents Must Register Their Vehicle Within 30 Days
If you move to Harris County from another state, Texas law requires you to register your vehicle within 30 days and get a Texas driver license within 90 days.
Once you live in Texas, you have 90 days to get a Texas driver license. You have 30 days to register your vehicle. In Harris County, registration also requires a passing emissions inspection. Harris County is part of the HGB ozone program, so most gasoline cars need that extra test.
Take your out-of-state title, proof of insurance, and a passing Texas emissions inspection to the Harris County Tax Office. If you moved from a state with no emissions testing, your car still must pass the Texas test. Check txdmv.gov for the full checklist for new residents.
Source to confirm: TxDMV – New to Texas