The practice of tipping-out is one of the reasons you should keep a detailed daily log of your tips.

If you documented that you tip-out, and you reported all your tips to your employer, then you do not include in your income the allocated tips in box 8 of Form W-2 (PDF).

When you report the cash tips you receive, you should first report the total tips, then the amount tipped-out. Publication 1244 (PDF), Employee's Daily Record of Tips and Report to Employer, includes Forms 4070 and 4070A, Employee's Report of Tips to Employer that provides lines to record:

The detail of the information provided should enable your employer to develop a reasonable, fair, and accurate method for determining whether tips need to be allocated, and, if so, how much.

Employers who operate large food and beverage establishments are only required to allocate tips if the total tips reported by all the employees who customarily receive tips are less than 8% of gross sales.

When there is a tip-splitting arrangement, it is important that all tips, including those received through tip-splitting, be reported to the employer by each employee who receives $20 or more in a month.