Social Security Taxes Cap

Hi Linda:

I understand there is cap on SS Taxes after $102,000.00
I have a six figure income. I was working for a another firm for the first quarter of 2008. I quit and joined another firm that I am currently employed with. Do I need to inform my present employer what I earned before I joined them, so they don't takes SS Taxes out after combining both the incomes. Or there is a form I will have to fill out for a credit at the end of the year?

Thank you