GAO claims to have saved a paltry $70B [0] in taxpayer dollars last year.
Here's them in 2022 saying $247B [1] got lost in that year due to "payment errors".
Looks like their job is to only make recommendations on spending and nothing more.
[0] https://www.gao.gov/blog/gaos-scorecard-how-we-saved-federal...
[1] https://www.gao.gov/blog/federal-payment-errors-known-improp...