No, absolutely not. You are to be paid for all time you work. An employer cannot withhold your pay for any reason. Furthermore, the Labor Code has mandatory requirements for the payment of wages, and going three weeks without pay is unlawful unless you are a salaried employee who qualifies for a monthly pay cycle.
If you want to press your rights, you can file a complaint with the Division of Labor Standards Enforcement who will assist in getting your proper pay, with penalties, at no charge to you.
Good luck to you.
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It is unlawful for an employer to pay you late. You should be paid at least 2 times per month in most cases. You can call an employment law attorney to discuss and he/she may take your case with no cost to you and attempt to get your wages plus more money in the form of penalties PLUS their fee. You can also file a claim with the CA Labor Commissioner. Many employment law attorneys offer a free initial phone consultation and may take your case without cost to you.
I certainly agree that wages cannot legally be withheld. At the same time, it may be beneficial to ask your employer in writing about the pay schedule and why it appears a weeks pay is being withheld before taking legal action. This may help protect your job by: (a) keeping a good relationship with your employer; and/or (b) if your employer retaliates against you for asking for your wages you have evidence of a complaint before the adverse employment action, which could support a wrongful termination claim.