If your employer reverses commissions should your gross be adjusted and taxes paid refunded back too you

Taxes paid are not refunded, but the yearly gross pay for the current year will be reduced by the amount charged back. (or normal way) the issues with taxes can be resolved when the employee files their yearly taxes.

Most of the cases I know, commission sales people are more often 1099 workers, and no income tax is withheld, but also, for most sales people on commission there is a fund set up, (where earnings are held) that have not been paid to emplloyee for charge backs to go against.

Your gross income is definitely adjusted, as are the taxes, if not by the employer, then when you file your tax return

While income taxes can be set right when you file your tax return, social security and medicare taxes that were initially withheld from the commission MUST be rebated to you by your employer when you pay back the commission.

Ebaines is correct. Make sure the FICA (Social Security and Medicare) withholding is properly adjusted, because fixing that issue direct with the IRS is both difficult and time-consuming.