Line 23: Do not deduct the following.
State and local sales taxes imposed on the buyer that you were required to collect and pay over to state or local governments. These taxes are not included in gross receipts or sales nor are they a deductible expense. However, if the state or local government allowed you to retain any part of the sales tax you collected, you must include that amount as income on line 6.
https://www.irs.gov/instructions/i1040sc
