As a move to introduce some form of performance‐related pay for teachers, a measure was introduced by government in 2000 by which teachers could apply for their performance to be appraised against a set of national standards and, if successful, would cross the performance threshold which would take them onto an upper pay range. To be eligible, teachers must be on point M6 of the main pay scale, and are required to submit evidence of their performance over the previous two to three years. The decision on whether their application to cross the threshold is successful rests with the head teacher. Success is dependent on the effectiveness of the applicant's teaching skills alone, and is not influenced by their performance in any additional duties or responsibilities they may have taken on, such as in a pastoral or management role. This measure was not welcomed by teachers' unions, who feared it would prove divisive; nor by many head teachers, who viewed it as administratively burdensome. It has not been possible to measure accurately its impact on school performance and quality of learning.
http://www.atl.org.uk/atl_en/pay/pay_calc/teachers/threshold/default.asp Details of threshold accreditation.