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In May 2007 Government introduced the revised impact assessment process to improve clarity and transparency of new regulations, including new requirements to summarise both the rationale for government intervention and evidence supporting the final proposal.
The revised guidance supporting this process is clear that impact assessments should be developed from the earliest stages of policy making in order to assess the costs, benefits and impact of regulatory proposals. This guidance is available at:
http://www.berr.gov.uk/bre