The Charity Finance Directors' Group and the Charity Commission are to collaborate to make figures on fundraising and management costs in annual reports more consistent.
The work, which will culminate in a special report due to be published in September, is intended to make comparative information between charities easier and less likely to be misleading.
It will feed into the next review of the Statement of Recommended Practice and could be adopted by the commission.
A project team, consisting of CFDG chief executive Shirley Scott, deputy chairman Les Jones and policy officer David Sinclair, will be joined by the head of the non-profit unit at accountancy Deloitte & Touche, Pesh Framjee, and the commission's policy accountant, Ray Jones.
The project will concentrate on improving input figures on support, management and administration costs, fundraising costs and valuing volunteers.
It follows last year's Strategy Unit report on charity law and status which called for the next charity SORP to "develop improved methods for apportioning costs and expenditure, enabling more meaningful financial comparisons to be made".
"CFDG is keen to ensure that the financial information provides enough of the right data to assist in this process," said Jones. "We will not be able to move onto meaningful comparisons until we are sure that we have got right the consistency and acceptance of fundamental principles of accounting for the inputs. This will, in turn, assist with the measurement of outputs, outcomes and impacts."
CFDG has warned that the project faced some tough issues on valuing volunteers, for example. Some charities believe that their work cannot be quantified.