How much of my cellphone bill can I write off? My business is strictly online and I use my phone A LOT for work.

[WillK · Accepted solution]

It depends. You need to calculate how much you use your cellphone for business and how much you used for personal use. 

For example, lets say your cell phone bill was $500.00 (used 100% of the time). You calculated that you used your phone 30% of the time for business and 70% of the time for personal. So $500.00 multiplied by 30%= $150.00. You can write off $150.00 as a business expense, and $350.00 would be a personal expense.