A group of students at Otley College near Ipswich cannot get their qualifications because they were not entered for exams.
The students were studying one day each week for two years on a carpentry course which ended in the summer.
But now they will have to wait until December to take the qualification exams for employment.
The college apologised for the mistake and said they will help support those seeking jobs.
In a statement, the college said: "We have made stringent steps to ensure that this won't happen again by implementing an administrative system that will eradicate problems of this nature arising in the future.
"We would like to express our profuse apologies to anyone else that may have been affected by this, as we have done previously."