Home office deductions are allowed for both self-employeds and employees. However, these deductions are limited to some strict limitations. For example, you can only use those expenses allocable to that part of your home. If your "office" is 13% of your home, you can only deduct 13% of expenses that benefit all of your home, including the office (ex. utilities).
In addition, if you are an employee, home-office expenses are considered miscellaneous itemizable deductions. Meaning in order to claim them, 1. it must be worth it to you to itemize, and 2. the only expenses allowed would be the amount that exceeds 2% of your adjusted income. Often times it is found that the deduction as an employee just isn't beneficial.
The hard part is proving that you are eligible to claim the deductions as the regulations regarding it are even stricter. It sounds like you're not eligible, but here is the gist of it.
The home must be the PRINCIPAL place of business meaning you must either:
1. perform "administrative/management" activities of the business at that location. You also must prove you perform those activities there more than you do at the office provided by your employer.
or 2. must be able to prove that the majority of your time is spent using your home office rather than the one provided by your employer, or that the activities performed there are more important.
So, if you're simply bringing home work for clients etc., you can not take the deduction. You can also find more information in Publication 587 provided by the IRS, which is accessible (if you have an Adobe Acrobat Reader) from their website at www.irs.gov.
Hope this helps!!
work in taxes :-)