If you earn money by providing goods or services, you must report the taxable income. The IRS doesn't care whether you incorporate, and the IRS doesn't care if there are state rules about registering a business that you did or didn't follow.
By default, a sole proprietor files a schedule C attached to their personal tax return. Schedule C lists the business expenses and income and calculates the net profit. The profit figure goes to the main form 1040 where it is added to your other income and expenses, and the profit also goes to schedule SE to calculate self-employment taxes.
An unincorporated partnership with your spouse is filed on two schedule Cs, one in each spouse's name, reporting half the income and expenses on each. An unincorporated partnership with anyone else needs a form 1065 partnership return, which is a different Turbotax program and has an early March 15 deadline. You can form an LLC or corporation, but you should have legal and tax advice before you do that.
You need to keep accurate business records of your income and expenses, regardless of whether you get tax reporting paperwork like 1099 forms from your clients and vendors.
