Pay cut without notice.

A prospective pay cut without notice is legal; a retroactive one is not. So say that on Friday, you are told that starting Monday, you will be paid $22k/year less; that is legal. BUT if you worked from Monday the 1st to Friday the 10th (two weeks; typical pay period), when you get the check for that payroll period, it MUST be at the salary or rate you had prevously been getting; when you work, you are paid the then-in-effect rate. Paying you less than that for work you did before being told of the pay cut is illegal; among other things, it is a breach of contract--violation of the agreement, even if oral or unwritten, between you and the employer pursuant to which you worked in exchange for a certain amount of pay. If not paid what you should have been paid, you could theoretically sue for the money, though you need to decide if doing so is worthwhile, since you could only sue for the lost pay until you found out they were cutting your salary; once you had notice, the pay cut is legal and effective.
(Once the employer tells you that your pay is lower going forward, if you keep working despite knowing that, the law concludes that you agreed to the pay cut--since otherwise, you could have quit or resigned.)