The introduction of planning, preparation and assessment time for classroom teachers from last month has added to school leaders' workload, while replacing management allowances with new teaching and learning responsibility points has "already impacted on workload and morale".
And while the pupil level annual school census should reduce the burden of data collection, its introduction from 2004, before some schools had the right IT equipment and training in place, has also "led to a huge increase in burdens for administrative staff".
The school workload advisory panel (SWAP) is also concerned that key curriculum reforms in Wales - including the play-based foundation phase for three to seven-year-olds, replacement of tests for 11 and 14-year-olds by moderated teacher assessment, and the broadening of 14-19 provision - could add to teacher workload.
The SWAP was set up in September 2004 as a result of the workforce agreement. The pound;60,000-a-year panel advises government and its agencies on cutting red tape and freeing teachers from excessive bureaucracy.
In its first annual report, published this week, it claims some success, for example, in reducing the amount of red tape associated with collecting data on pupil attendance and making inspectors more aware of the need to reduce the bureaucratic impact of their work on schools.
Chairman John Hopkins, head of Gwernyfed high school, near Brecon, highlights the trialling of "impact assessments" by the Assembly government as one of the most important developments of the year. These are meant to ensure that the implications for workload in schools are considered right from the start of developing new policies.
He added: "Our strategy of working with Assembly officials at a relatively early stage has already begun to have an effect in stripping away layers of bureaucracy from new initiatives."
But the SWAP report says schools are still receiving multiple demands for data from different organisations, and that the paperwork associated with special educational needs pupils is "excessive". Jane Davidson, education and lifelong learning minister, said officials regularly sought SWAP's views on how burdens might be reduced.