Thank you very much for your reply and clarification. These deductions are absolutely illegal pursuant to California law.
As a general matter, California law zealaously protects an employee's earned wages and permits forfeiture only in certain extremely limited circumstances. One such circumstance in which compulsory deductions from wages is permissible is in instances where an employee's gross negligence or willful misconduct cause harm to the employer.
While having someone fill in for you on a cleaning may, on some level, have constituted ordinary negligence, it in no way rises to the level of "gross negligence" (that's for things like crashing a company vehicle while under the influence of alcohol) and certainly does not constitute a willful actu of miscnoduct (i.e. taking a baseball bat to a company computer). Thus, while your employer would be free to discipline you for this incident (and even terminate you if they saw fit), they CANNOT deduct from wages you have already earned.
With regard to your commission adjustments, that too is illegal and constitutes a breach of contract. If employers could simply adjust commissions whenever they saw fit, commission agreements would have no meaning whatsoever, since payment would simply come down to what your employer "felt like" giving you.
You can obtain compensation for these wrongful deductions by filing a wage claim with the Department of Labor Standards Enforcement. To file a wage claim with the DLSE, visit this link: http://www.dir.ca.gov/dlse/howtofilewageclaim.htm
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