If you change jobs or moonlight, an accounting headache awaits you. Not even the FTB is sure how to untangle the mess. It shouldn't be much of problem for companies that farm out their payroll tasks, but many small businesses can't afford to do so. Tax experts worry about those that tackle payroll manually or who neglect to acquire updated software. Eventually, someone will catch the shortfall, but it might not come until the end of the year, when penalties and interest have built up.
Employers can ask workers to make up for the company's goof, but workers can decline.
Many companies will simply eat the difference, experts predict.