The short answer is:
If you are self-employed (side gig, independent contractor, etc.) you report all your business income and expenses on Schedule C, an attachment to your tax return. You are expected to keep accurate records of your income and expenses, even if you don't get tax paperwork from your customers or clients. Your gross income minus your expenses equals your taxable income or net profit. That flows to the main form 1040 where it is added to your other income, deductions, dependents and credits to calculate your income tax. You also pay 15% self-employment tax on your net profit, this is the equivalent of social security and Medicare taxes for self-employed people. The combined income tax and self-employment tax is your total tax due.
You are also expected to make quarterly estimated tax payments from your self-employment income. If you don't make quarterly payments, you may owe an under-payment penalty even if you pay in full when you file your return. If you are single with no dependents, somewhere between 30% and 40% of your business profits will be taxable.
As a ride-share driver, your main expense will be mileage on your vehicle. You can deduct about 57 cents per mile for the work miles you drive making deliveries, as long as you keep records of your mileage. That amount includes allowances for gas, repairs, insurance and wear and tear. There is another method for deducting vehicle expenses that is more complicated and usually results in less of a deduction for most people, someone can explain it later if needed.
