actually it is you who is not understanding. so let me help a Brit out.
the US has 3 Branches of Government & key to those 3 branches is the separation of powers.
the US Government Accountability Office (US GAO) is a branch of the Legislative. the same branch as the Congress. The US Government Office of Accounting was created in 1921 & in 2004 changed Accounting to Accountability, (i am sure nothing else changes as a result *snark)
yes the legislative does make laws & if those laws are sound & do not harm the separation of powers, or extend the power of Congress