That actually does not account for the error message. Even though you cannot take a home office deduction in a year where your business does not earn a profit, you should be able to determine the amount of the deduction and, as you say, carry it forward to another year. The software worked exactly that way last year, but this year, it is failing to do so.
As it has done in previous years, TurboTax should allow you to determine your home office deduction for 2020, then disallow it for 2020 if your business did not earn enough. It should then carry that home office deduction forward to next year. But if you delete the home office deduction entirely, TurboTax cannot compute the home office deduction to carry forward. For the tax year 2019, my business did not earn enough for me to claim a home office deduction. That amount was computed by TurboTax, though, and rolled forward to this year. In the 2020 version of TurboTax, the software has a bug and will not allow the return to pass its review. It is errantly putting a negative number in Line 10 of Form 8829, Deductible Mortgage Interest, which is causing the problem.
