A recently released report by the Special Inspector General of Afghanistan Reconstruction (SIGAR) has indicated that the US lost $19 billion in Afghanistan to “waste, fraud and abuse” since 2002. SIGAR has the authority to audit, investigate the programs undertaken by the funds sanctioned through US Congress in Afghanistan. 
Since 2002, the US has spent around $134 billion in Afghanistan for reconstruction and various other projects.

“Of that amount, SIGAR reviewed approximately $63 billion and concluded that a total of approximately $19 billion, or 30 percent of the amount reviewed, was lost to waste, fraud, and abuse,” the report, that was released on SIGAR's website, said 

Between January 2018 and December 2019, $1.8 billion lost due to waste, fraud, and abuse, says the report. Around $1.45 billion of wastage caused due to “ineffective and inadequate control.”

A sum of $1.6 billion allotted for the purpose of counter-narcotics programs, SIGAR believed, wasted totally without achieving any significant objectives.

Corruption, mishandling, and lack of oversight in the utilization of these funds remain key concerns for donor countries and will affect the future commitments to Afghanistan, the report warned. About 75 percent of the total expenditure of the Afghan government comes through donations from other nations.

The World Bank estimated that Afghanistan will require between $4.8 billion and $8.2 billion annually at least till 2024 in the form of donor support even in a post peace environment in the country.

SIGAR, apart from auditing and investigating reconstruction programs, also provides recommendations for better use of funds. Its recommendations, SIGAR said, resulted in saving of about $3.2 billion in US taxpayers’ money. 

“Endemic corruption, widespread insecurity, and lack of accountability over on-budget assistance continue to make any investments made in Afghanistan vulnerable to waste, fraud, and abuse and may threaten the peace process as well as the perceived legitimacy and effectiveness of the Afghan government,” the report concluded.

In one of its earlier report, SIGAR termed the problem of endemic corruption in Afghanistan as a strategic threat to the stability of the Afghan government. 

Link for full report - https://www.sigar.mil/pdf/special%20projects/SIGAR-21-05-SP.pdf