What is sufficient rent and utility documentation for home office?
This certainly can raise a red flag to the IRS, as it is frequently over-estimated and over-valued. AFAIK the space so classified as a home office needs to be used for business use, exclusively. If the area so named is 10% of the entire unit, and used exclusively for business (hard to prove). Then you could legally deduct 10% of the monthly bills of the entire unit. If said area sees business activity, 3 days/month, then you can deduct 10% of the 10%. Usually not worth it.