(a) Upon approval of the H-2B Registration, the employer is authorized for the specified period of up to 3 consecutive years from the date the H-2B Registration is approved to file an Application for Temporary Employment Certification, unless:

1. (1) The number of workers to be employed has increased by more than 20 percent (or 50 percent for employers requesting fewer than 10 workers) from the initial year;
2. (2) The dates of need for the job opportunity have changed by more than a total of 30 calendar days from the initial year for the entire period of need;
3. (3) The nature of the job classification and/or duties has materially changed; or
4. (4) The temporary nature of the employer's need for services or labor to be performed has materially changed.