What two requirements may block renewal besides fees?

The correct response identifies smog certification and proof of insurance as critical requirements that can hinder the renewal of vehicle registration beyond just the payment of fees.

Smog certification, often required in states with specific air quality standards, ensures that vehicles meet environmental regulations related to emissions. If a vehicle fails to meet these standards, the registration renewal will be blocked until the necessary repairs are made, and the vehicle passes a smog check.

Proof of insurance is another vital requirement for vehicle registration, as it demonstrates that the vehicle owner has the necessary coverage to operate the vehicle legally. Without valid insurance, the registration cannot be renewed, as this would not only violate state laws but also pose risks to public safety.

Factors like emissions testing and proof of purchase or other requirements may play roles in specific situations but fall outside the primary concerns for renewal blocking mechanisms in many states. Similarly, an inspection and safety check can be necessary for all vehicles or new ones but are typically not prerequisites focused strictly on renewal. Title transfer and registration forms pertain more to changing ownership or initial registration rather than the renewal process itself.