The commissions earned from your real estate busines should be reported on Schedule E of the tax return.
The amount of tax that is due is based on a number that is
"the sum of the net self-employment income x SE Tax rate (approx 15.3%) + Net self-employment x regular tax rate".
The net self-employment income from the Real estate business is equal to Gross Commissions minus the costs/expense related to the real estate business.
You can claim items such as, auto travel, business cards, cell phone, postage, brochures, lock box, real estate licenses, continuing education expenses, meals and entertainment expenses...web site expenses if you have one etc...and any other expenses directly related to the real estate businesses.