The Department of Defense isn't getting any better at managing its money, a new Government Accountability Office report shows.

DOD's total assets — which account for 33 percent of the federal government's — may not be fully accounted for. This includes inventory worth $254 billion and property and equipment worth $1.3 trillion, according to the GAO report.

The Pentagon is also unsure how much money in improper payments it has doled out because it has a flawed way of recording them. This also prevents the issue from being fixed, the report says.

GAO also found 75 violations of the Antideficiency Act — a federal law intended to prevent DOD employees from spending money that violates agency regulations — costing a total of at least $1.1 billion. But the auditors couldn't be sure about that figure, because DOD's method of monitoring the number of violations and how much they cost was found to be flawed as well.

DOD also continues to make poor "cost-effective choices," according to GAO.

The Air Force's Expeditionary Combat Support system, intended to help manage logistics, was cancelled in December 2012 after spending more than $1 billion, and deadlines were continuously missed, for example.

DOD also struggles to consistently report to Congress how much its weapons systems cost, preventing any effective oversight of the costs.

The problems "significantly impair efforts to improve the economy, efficiency, and accountability of the department’s operations," the report said.

GAO pointed out that though DOD is currently taking on the issues, many won't be resolved until 2017.

"Until fully resolved, these weaknesses will continue to adversely affect DOD’s ability to achieve its goals for financial accountability, including the ability to produce consistent, reliable, and sustainable financial information for day-to-day decision making," the report said.