Legal Question in Employment Law in California

Yes, it is illegal for an employer to require an employee to work off the clock. Employers must pay its employees for all time worked and are required to keep an accurate record of that time so the employee is paid correctly. If the employer is cheating you out of wages by not paying you for all the time worked, you have legal options. Make sure you keep an independent record of all hours you work in case you need it to prove you worked those hours.

Absolutely illegal.