Not true. It means the server pays taxes on $8 of your check, because the gov't assumes the server is receiving at least an 8% tip. So if the server is taxed at a rate of 25%, they will be paying taxes on 25% of $8, or $2. The 25% tax rate is just thrown out there as that number will depend on the server's overall annual income and the tax bracket that they fall into. I just threw out 25% as an example.
The point still exists that many people misunderstand this and assume that, like in the case of a $100 check, of you don't leave at least $8, then the server is actually paying to serve you. Not true. It would mean that for that particular check, they are being taxed at a higher percentage than normal because they are not receiving the amount in tips that the govt is taxing them on. But if, hypothetically, they are taxed at 25%, they are not actually "paying" to serve you unless you tip less than $2.
You also have to consider the fact that majority of customers will always tip far more than 8%, so even when a server receives an occasional low tip or is stiffed, it's all going to more than balance out when the tips of the rest of the tables are calculated in. Also, despite what any manager wants to say, they cannot force a server to claim more in tips than what they actually received, even if the number is less than 8% of the total sales. I ran into this one night while serving where I sold over $400 in food, and only made $12 in tips. I was supposed to claim around $35. Just to make minimum wage for the evening, I needed to claim at least $16.50 in tips (base pay plus tips divided by hrs worked to equal min wage). I claimed what I actually made, which was my legal right. Had I made less for the entire pay period than min wage, the store would have had to cover the difference. My tips from the other nights that week more than covered the low tips from that one night and took me far ahead of both minimum wage and the 8% of my total sales for the week. Servers get away with only claiming 8% of total sales in tips, even though they generally make far more. But you are only taxed on what you claim and you cannot be forced to claim more than you receive.
Now, I'm not taking any sides on what people choose to tip, just saying that regardless of what you tip, the server is guaranteed to make at least minimum wage, and in a pay period if their tips do not equal at least 8% of their sales, by law, they do NOT have to claim (or pay taxes on) more tips than what they receive.