My child put the wrong SSn down on her peperwork when she started her job,When I looken at her W2 I saw that it was my SSN! Will this affect my taxes and how do I fix it?

Yes, since the earnings are being recored against you,

She needs to go to where she works, get the social security number corrected, and have them report it correcting to the IRS.

I would assume as soon as you told her she rushed to work the next day and had it corrected ?

Also how did she do it, since her work place is suppose to have to physically see her card? Something sounds wrong here ? What type of business and earnings is it?

Make sure it's also corrected with the SS Administration. I lived with an unexpected typo on my SS payments from my employer for years before I found out about it. It wasn't hard to correct, but a little disappointing to find out I wasn't really going to get as much as the person with that SS# was going to get.

The employer to submit a corrected W-2 (Form W-2C) to the IRS and SSA. It should take about a week before you get the corrected W-2.