Self-employed professionals struggle to correctly allocate vehicle mileage across multiple business activities for tax compliance

Freelancers and small business owners with multiple income streams (e.g., Schedule C consulting work plus Schedule E rental property management) face confusion about whether they can combine business mileage across different business activities to meet the IRS 50% business-use test for vehicle deductions. Current tax software and guidance don't clearly address this scenario, forcing professionals to either guess, hire expensive CPAs, or risk audit exposure by making incorrect allocations.