It depends what the mortgage company looks at, your gross income or taxable income, etc. If you enter mileage and home office expenses, they may lower your income.
Per How To Get a Mortgage If You're Self-Employed - Bankrate.com When it comes to filing your taxes, keep in mind that lenders consider your total income to be the amount after deductions and not what you gross before those adjustments. This means all of the expenses you write off for business that may benefit you at tax time may not necessarily be in your favor when you’re applying for a mortgage.
“The hardest part can be to show that income. It’s a real fine line. A lot of the time [potential borrowers] are trying to maximize all of their deductions. It’s a lot of paperwork,” says Dougherty.