Legal Question in Employment Law in California

Generally, no. An exempt employee must receive a salary, which is a fixed monthly (or more frequent) amount, equal to double the minimum wage for full time employment. In other words, they need to be paid at least $4,506.67 per month in order to meet the "salary test" under the so-called white collar exemptions (executive, administrative, professional). An employer can't pay less than that and then "make up the difference" with a one-time payment. There are other exemptions that would not need to meet this threshold, but based on your question it appears you are asking about the white collar exemptions.

You should consult with an attorney if you feel rights are being violated in any way by your employer.