IRS Publication 587, on Business Use of your Home, says this:

"If you cannot deduct the business portion of your home mortgage interest in full this year, you will carry over the remaining home mortgage interest to a subsequent year in which you use actual expenses to figure your business of the home deduction."   and

"If you cannot deduct the business portion of your real estate taxes in full this year, you will carry over those real estate taxes to a subsequent year in which you use actual expenses to figure your business of the home deduction."

If you can, in fact, deduct these items even in a year with no business income, why would the IRS talk about carrying them forward?

Thank you!