1) You must include any income that you have received during tax year 2018. You'll be receiving a 1099 from the company that should include all the commission that you were actually paid. Be sure that the amount shown on your 1099 agrees with the amount you actually received. DO NOT include income that you have not received.
2) If you incurred expenses during 2018, you should enter all of those qualified business expenses in your 2018 tax return. This will decrease your tax liability for tax year 2018.
3) When you receive compensation of commissions that you were owed, but not paid, (hopefully in 2019), you'll enter that income in the return for the tax year in which you receive it.
*** I am NOT a tax expert. I am a seasoned TurboTax user, and volunteer to provide assistance to TT users. Nothing I post is to be considered TAX ADVICE; I bear no legal liability for responses.***
