You have nothing to report on your tax return concerning this, since the property is not "in fact" a rental property with your intent being to produce rental income. So this property is not reported as such on SCH E at all. Now if this was a rental property in 2018 that you reported on SCH E before your brother moved in, and you did not convert it to personal use on your 2018 tax return, then you'll need to convert it to personal use on your 2019 tax return with a conversion date of 1/1/2019.
Additionally, since your brother lives in the house as his primary residence, that means he has a legally vested interest in the property. Since he paid the mortgage interest and property taxes and can prove he did so, that proof combined with his proven vested interest gives him the right to claim the mortgage interest and property taxes as a SCH A itemized deduction on his return. You have no right to claim any deductions on the property, (not even as a SCH A itemized deductions) since you did not make the payments.
