Home Office Tax Deduction Simplification and Improvement Act of 2009 - Amends the Internal Revenue Code to allow a taxpayer who uses a residence to conduct a trade or business to elect a standard tax deduction equal to the product of a standard rate determined by the Secretary of the Treasury and the square footage of the portion of a residence used to conduct a trade or business (home office tax deduction). Modifies the rules for the home office tax deduction to: (1) allow a deduction for the cost of dealing with patients, clients, or customers even if they are not physically present in the home office; and (2) establish a de minimis exemption for personal use of a home office.
Requires the Secretary to ensure that all self-employment tax forms and schedules separately state amounts attributable to real estate taxes, mortgage interest, and depreciation for purposes of the home office tax deduction.