Schools are appealing when exam results just miss crucial grades as a “one-way bet” to up marks, says the exams regulator.
Ofqual boss Glenys Stacey vowed to make the system more “fair, transparent and effective” after it found schools appeal “tactically”.
A report says: “Where marks are just below a key grade boundary, the likelihood is their grade will improve or stay unchanged.
“As the pressure to deliver results increases, so do the incentives to appeal.”
Twice as many exam papers were sent back for appeal last year than in 2009.
The regulator aims to have a fundamental redesign of the exams system in place in the summer of 2015.