Had a roof leak that only affected my home office. Can I take the roof repair as a home office business expense?

If the leak only affected the home office and the repair was only to the home office portion of the roof, then you can deduct 100% as related to the home office.

If you repaired more than just the home office roof area, then you would report the repair as a whole house repair and only a portion would be deducted as related to the home office.