IRS changes my 2005 taxes to 'pro', charges me self-empl tax

[Benholio]

I claimed roughly 25k in 'other income' on my 2005 tax return, and had no other income. I received a notice that I now owe ~$2100 in self-employment taxes on that income.

I knew there was a chance this would happen, since I had no other income on my return. I do have a question, though, for anyone who has dealt with this before.

Inclosed is a form, 886-A, 'Explanation of Items', where it asks me to provide information about my 'other income' so that they may determine whether it is subject to self-employment tax.

The categories for this form are "Trade or business", "Hobby", "Prize", "Odd job/contract labor", "Other", and "reimbursement for expenses that were paid and deducted from your incomine in a previous year".

Do you think there is any chance that using the "Hobby" category will help here?

Any other advice?