Generally, no fees will be assessed on stock option exercise / assignment activity. Australian and Hong Kong stock options are an exception where fees will be passed through. US stock options will be subject to Section 31 and FINRA TAF regulatory fees.
Index options will generally be charged standard commissions, with the exception of US index option exercise / assignment activity which will not be subject to fees.
Futures and future options will be subject to standard commissions for expiration or exercise/assignments.
For more information, please refer to the Exercise and Assignment table and the Commissions page of the IBKR website.