You do not add your daughter's income to your tax return (filing). If she has enough income**, she has to file her own return.
If you use your car for your self employed business you may deduct either the standard mileage rate ($0.545/mile) or the business percentage of actual expenses. Actual expenses includes depreciation.
**Your dependent must file a tax return for 2018 if he/she had any of the following:
1. Total income (wages,
salaries, taxable scholarship etc.) of more than $12,000 ($6350 in 2017).
2. Unearned income (interest,
dividends, capital gains) of more than $1050.
3. Unearned income over $350 and
gross income of more than $1050
4. Household employee income
(e.g. baby sitting, lawn mowing) over $2100 ($12.000 if under age 18)
5. Other self employment
income over $400, including box
7 of a 1099-MISC
Even if he had less, he is allowed to file if he
needs to get back income tax withholding. He cannot get back social security
or Medicare tax withholding.
In TurboTax, he indicates that somebody else
can claim him as a dependent, at the personal information section.
