One requirement for the home office deduction is that you use a part of your home as your principal place of business. This doesn't necessarily mean that the majority of your business activities need to take place in your home office. What it does mean is that you use your home office regularly and exclusively to administer or manage your business and that substantial administration/managerial activities aren't conducted at any other fixed location.
If you have a regular job in addition to self-employment: The "principal place of business" question refers to your self-employment activities, not your regular job.
Example: Erin just started their consulting business and has designated a spare bedroom as their office, which is used exclusively for business. About 85% of Erin's time is spent outside the home, meeting potential clients in various restaurants and coffee shops. However, they do all scheduling, planning, and bookkeeping from their home office. These administrative and managerial activities qualify their home office as their principal place of business, even though they're spending 85% of their time outside of their home office.
