Daryl Jacob has appealed against the 10-day ban handed out by the Wincanton stewards for failing to ride out to the line on Ulis De Vassy last Thursday.
Should the suspension stand, Jacob would miss the lucrative Christmas period, where he could have expected to be riding plenty of top-class horses for Paul Nicholls, who employs him as second jockey to Ruby Walsh.
The dates of his suspension mean he would sit out December 20-22, 26-31 and January 1.
Jacob had been in line for the mount on Kauto Stone in the King George VI Chase at Kempton on Boxing Day after partnering him to victory at Down Royal last month. He would also miss Chepstow's Welsh National meeting.
Jacob was in front over the last flight on the Nick Williams-trained Ulis De Vassy in the Racing Welfare Fox-Pitt Eventing Handicap Hurdle but was headed inside the last 100 yards by Quaddick Lake.
It appeared that Jacob mistook a path, several strides before the line, as the winning post, before realising his error and riding out for a couple of strides more.
The stewards punished him under Rule (B)59.4 as they believed he still could have won. The official winning margin was a neck.
His appeal will be heard on Thursday.