ICH harmonisation activities fall into 4 categories: Formal ICH Procedure, Q&A Procedure, Revision Procedure and Maintenance Procedure, depending on the activity to be undertaken (see below).

New topic for harmonisation of ICH?
Concept Paper & Business Plan required
Clarification needed for an existing ICH Guideline?
Concept Paper required (Business Plan may be required in certain cases)
Content of an existing ICH Guideline out of date or no longer valid?
New information to be added to an existing ICH Guideline?
Concept Paper required
Change to be made to elther Q3C Guideline or M2 Recommendations?
Proposal/Concept Paper required for Q3C maintenance. No Concept Paper required for M2 Recommendations maintenance

Each harmonisation activity is initiated by a Concept Paper which is a short summary of the proposal. Depending on the category of harmonisation activity a Business Plan may also be required. The Business Plan outlines the costs and benefits of harmonising the topic proposed by the Concept Paper.