Jersey Bulls, who had a 100% record in their debut season and had already secured promotion, look set to miss out on going up now after the FA announced that seasons in steps 3-6 of the non-league system would be brought to an immediate end.
The FA says results in those divisions, including the Isthmian South East where Guernsey FC play, will be expunged.
It means the Bulls' perfect record of 27 wins from 27 in Combined Counties Division One will disappear from the record books, with the club forced to start from scratch at the same level next season.
The FA's knockout competitions, including the Inter-League Cup - in which Jersey's representative side have reached the last four - could still be completed, however.
Jersey Bulls' committee met on Thursday evening, following the announcement.
In a statement, chairman Russell Le Feuvre said the club were "disappointed" with the decision and that they would be "engaging further" with the FA and Combined Counties Football League.
WATCH this clip with Bulls caption James Querée...