Wife sold sewing items on Etsy. What percentage of the monthly wifi can we deduct as a cost of doing business expense?

[AnnetteB6]

You will need to determine the percentage based on how much the internet service is used for business purposes versus personal purposes.  There is not a set amount that is acceptable to claim as a business expense.

Take into account the number of people in your household and how much time each individual uses the internet on a daily basis.  If you have a reasonable way to determine the percentage that you are claiming as a business expenses, then there should not be a problem if your return happens to be examined by the IRS.  

[Opus 17]

Remember that if audited, you must prove every deduction to the satisfaction of the examiner.  You will need some way of determining the business percentage that takes your particular situation into account, and you will need to keep those records for at least 3 years. 

[AmeliesUncle]

Does she have a qualified Home Office (used regularly and EXCLUSIVELY for business)?  If so, internet is usually entered as a Home Office expense (utilities), and the amount of the deduction would be the business percentage of your home.