It's recommended to have a tetanus shot every 10 years and if you've had a tetanus shot and it hasn't been 10 years yet then you don't need another tetanus shot.
But you may get a booster shot if you need to.
If you get a puncture wound and need a tetanus shot you need to get the tetanus shot within 48 hours of getting the puncture wound otherwise you risk infection and possibly death from the infection.