8829 Instructions, bottom of page 2

Taxpayers claiming the standard deduction. If you claim the standard deduction, you will not include any mortgage interest, mortgage insurance premiums, or real estate taxes on lines 10 and 11; instead, you will claim the entire business use of the home portion of those expenses using lines 16 and 17. If you are not increasing your standard deduction by a net qualified disaster loss, then you will not include any casualty losses on line 9; instead, you will claim the entire business use of the home portion of your casualty losses on line 29. If you are filing Schedule A to increase your standard deduction by a net qualified disaster loss, see Casualty losses reported on line 9, later.

You may prefer to itemize your deductions on Schedule A to claim amounts on lines 9, 10, and 11, even if your total personal deductions are less than the standard deduction.