United States tax law says that to claim a deduction for a home office, the space must be "regularly and exclusively" used for business purposes.

Does "exclusively" here mean absolutely 100%? Like, suppose someone had a home office, worked there 8 hours a day, 5 days a week, 52 weeks a year, and one day while sitting in his home office he gets a toothache so he spends 10 minutes calling his dentist to make an appointment. Does he lose the deduction for the year because of 10 minutes out of 2000+ hours?

(BTW, someone might say, Go ahead and claim the deduction. How would the IRS ever know you made that phone call? But let's assume we're going to be completely honest on our tax return here. I'm asking what the rules are, not what rule-breaking I might get away with.)

I work from home. My employer no longer even has an office, all the employees work from home. When I got the job I set aside a room in my house to be my office. I've never claimed a home office deduction, but I wonder if I could. In my case, I have a printer in my office that I use for both personal and business purposes. I never saw any point in having a separate printer for personal use in another room. Sometimes after work I will read news web sites or search the Internet for jokes. Etc. Is there some rule about "minimal personal use"? Or some standard that 90% of the time (or whatever number) you're in that room you must be working? Or some "reasonableness standard"?

It seems to me that if "exclusively" is taken absolutely literally 100%, that almost no one would could legitimately claim a home office deduction.

  • You might want to update your question with reference to irs.gov/businesses/small-businesses-self-employed/… and irs.gov/pub/irs-pdf/p587.pdf Note the Recordkeeping requirements. Feb 12, 2018 at 10:44
  • @MorrisonChang I've read 587 and I briefly looked at your other link. If there's something in either of those documents that answers my question, could you please be more specific? Perhaps I missed it.
    – Jay
    Feb 12, 2018 at 19:39
  • Your example is a bad one - that's you using your actual office for a personal call. That's completely different from using the office not as an office. My home offices are literally only used as offices - there is never, ever, Other Home Use (living room, TV room, bedroom, kitchen, hallway, visiting room, etc).
    – Fattie
    Feb 13, 2018 at 16:24
  • @Fattie That's my question: what constitutes using it "not as an office"? I want to know if X is okay and Y is not okay. If X is okay, that doesn't make it "a bad example", that makes it an example where the answer is "okay". :-)
    – Jay
    Feb 13, 2018 at 18:27

1 Answer 1


Even in a regular job you make personal calls.

What you don't want is a guest bed in the office. Have the office full of business stuff.

I have some old books and hardware that I could probably throw out but I leave that office full.

  • 1
    +1 Agreed. It’s not that you are forbidden from talking to your family in the office. “Exclusively” here means that this room is just an office and not an office/bedroom, office/dining room, office/home theater, etc.
    – Ben Miller
    Feb 12, 2018 at 22:13
  • "Even in a regular job you make personal calls." Sure. That's why I was wondering about the definitions. When I've worked at a regular office, people chat with friends, eat lunch, make personal calls, copy personal documents on the office copier, etc etc, and I've never heard of that endangering the company's ability to take a tax deduction for the office. That's why I asked.
    – Jay
    Feb 12, 2018 at 22:54
  • 2
    It would be nice to have an authoritative source for these claims.
    – BrenBarn
    Feb 13, 2018 at 8:28
  • @BrenBarn Exactly. "This sounds reasonable to me" and "this is the law" are not necessarily the same thing. I think a fair and reasonable rule would be something like, "only minimal personal use, like chatting with a friend or family member or eating lunch at your desk". But what the law actually requires and what I think is fair are often very different.
    – Jay
    Mar 23, 2023 at 21:26
  • Authoritative source: Websearching "irs home office deduction" finds the IRS's statements about what does and doesn't qualify.
    – keshlam
    May 17, 2023 at 22:14

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