As required, the Congressional Budget Office (CBO) reports each January to the Congress on the following:
That requirement is specified in section 202(e)(3) of the Congressional Budget and Impoundment Control Act of 1974. The purpose of that provision is "to help Congress use the early months of the year to adopt authorizing legislation that must be in place before the regular appropriation billss can be considered."
(Note: CBO publishes three versions of the report on Unauthorized Appropriations and Expiring Authorizations each year, which differ only in the way that Appendixes A and B are sorted. In those reports, the appendixes are sorted by House and Senate authorizing committees and by Appropriations subcommittee.)