IBKR does not charge a fee when you request and add trading permissions to your account. The requirement for trading permissions is that you meet the qualifications.
Additional Information
Is there is fee to request trading permissions?
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Why was my order rejected with "Error 503"?
Why did some of my paper trading orders show as filled after the close?
Are there any extra fees or commissions when selling stock?
Are the trading commissions listed on your website inclusive of the spread?