Can I claim the home office deduction for two or more businesses?
Yes, assuming the other qualifications are met. The only caveat is that if you use the same office for multiple businesses, you can't deduct the office expenses multiple times; you have to split them between the businesses.
On the other hand, if you have separate offices for each business, for example one in the house and the other in the garage, you'd just enter the pertinent information (square footage, etc.) for each office space when you enter the information for each business.