Okay, that's the problem--your number and words don't match up. What I think you're actually talking about is the Payroll Tax that goes to the Social Security Administration. As it stands, currently you and your employer pay 6.2% of your wages--but only the first $102,000 of wages--in Payroll Taxes. That figure is called the Social Security Wage Base. From what I've read, Obama is proposing is that we raise the Social Security Wage Base to $250,000.
So unless your dad is employing a mechanic making more than $102,000, he won't be paying a dime more in taxes from what I can tell.
+++++
I think the problem is that there are a couple of tax increases that Obama is proposing that have that $250,000 magic number. It seems he's also proposing that if you make more than $250K, your dividend tax rate and your capital gains tax rate will both go from 15% to 20%.
Which mean Warren Buffet will come a little closer to paying the same percentage in taxes as his receptionist, who currently loses about twice as much of her income percentage wise to taxes as the world's second richest man who made 46 million dollars last year. [http://www.washingtonpost.com/wp-dyn/content/article/2007/06/27/AR2007062700097.html?hpid=sec-politics]