When something absolutely has to be done and cannot be put off, use the adjective imperative. Imperative is from Latin imperare to command, and its original use was for a verb form expressing a command: Do it! is an imperative sentence. It's still used that way, but it's more commonly applied to something so pressing it cannot be put off: Hiring new workers has become imperative..
1 A tandem (dual) axle utility trailer starts at $1,200-$3,000 depending on size and weight capacity, and it can cost $4,000-$7,500 or more for commercial-quality utility trailers.
Basis of tax for trailers; permanent license plate. (1) For each privately owned utility trailer or travel trailer, which is not operated for hire, lease, or rental, twelve dollars ($12). (2) For each utility trailer, rented or leased for compensation of any kind or nature, fifteen dollars ($15).