Guidance documents will be produced to address the concerns of charities working in the prevention and relief of poverty, the advancement of education, the advancement of religion and fee-charging charities.
The drafts will be put out for consultation for three months.
The publication of the final versions of the four documents will be staggered over the second half of 2008.
Charities will be expected to start reporting on public benefit at the end of the financial year 2008/09.
The commission said it would let each organisation decide how long its report should be.
Because charities have up to 10 months to file reports, trustees now have nearly two years to familiarise themselves with the guidance and what it means for their charities.
The Government has pledged to carry out a review of how public benefit is working in three years' time.