De Sousa, 35, was given an 18-day suspension, with six days deferred.
The Brazilian was found guilty of using his whip without giving Swiss Cross time to respond at Lingfield on 16 June, triggering a suspension of between two and six days.
As it was his fifth such infringement within the previous six months, it was referred to the BHA.
He will be banned for 12 days (1-13 July inclusive when Flat racing takes place) under the ruling body's totting-up procedures.
Six days were deferred for 42 days and would be triggered by any further disciplinary breach during that period.
De Sousa will miss the Coral-Eclipse fixture at Sandown and the July meeting at Newmarket.
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Champion jockey Silvestre De Sousa faces 12 days on the sidelines after breaching rules on use of the whip.