So I work from home a few times a month. I use my iMac to do all my work on those days. Is there a particular rule to being able to write-off the cost of the iMac? Or do I have to write-off a particular % of it's cost? I would say I work from home 5 days a month which is approximately 40 hours/month. This could be equated to 25% of my work hours per month. Does this mean I can write off 25% of the total cost of the computer? Or can I write-off more? less? I'm searching the IRS pages for answers too, but anyone with experience of knowledge would greatly save me some time.