The criteria are as follows:
If you were an employee (pay reported on W2), and this was income in your trade or business, and you reported it in a previous year under a claim or right-(which means you thought that you had unrestricted right to the income)--if you repaid over 3000 dollars in 2005, you can take either a credit or a miscellaneous deduction, whichever benefits you more.
The instructions on how to compare the credit or deduction can be found in Pub 525. Here is the link, it is towards the end of the page:
http://www.irs.gov/publications/p525/ar02.html
Best of Luck with your situation. If you feel I answered fairly, please hit "ACCEPT". If not, let me know! Feedback and bonuses welcome!
Wendy D. Rieger, Enrolled Agent