I received personal checks as a part of my contract work in 2008 for 4 months. Did not receive a 1099 Misc from the employer.

Worked with a CPA filed that income and paid taxes through Form 941 for my C corporation. Received W2 from my company for that income.

Filed that W2 with my 2008 1040 tax returns.

Yesterday IRS sent me letter to pay the taxes for unreported 1099 Misc income on my SSN# since that employer sent IRS on 5/2008 as part of his 1099 Misc reporting that the amount he paid me.

How do I address IRS now ?

Please advice me.