Large food and beverage businesses (where tipping is customary and more than 10 employees work on a typical day) file IRS Form 8027. If all reported tips together come to less than 8% of gross receipts, the employer has to allocate the difference among tipped employees.
Allocated tips show up in box 8 of your W-2. No tax is withheld on them, but you may owe income tax and FICA on them when you file, unless your own records show you really received less.
The best protection is a daily record of tips received and tip-outs paid. See reported tips.
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