The Internal Revenue Service recovered $576 million in erroneously issued tax refunds last year thanks to outside tips provided by financial institutions and other sources such as tax preparers, more than double the amount from three years ago.

A new report from the Treasury Inspector General for Tax Administration examined the IRS’s External Leads Program, which receives leads about questionable tax refunds identified by a variety of organizations, including financial institutions, brokerage firms, government and law enforcement agencies, state agencies and tax preparers. The questionable tax refunds include Treasury checks, direct deposits and prepaid debit cards.

The program helps the IRS to recover erroneous tax refunds and save money, but the TIGTA report noted that improvements are needed to ensure that the IRS verifies the leads on a timely basis.

The External Leads Program has grown from 10 partner financial institutions returning $233 million in calendar year 2010 to 258 partner financial institutions and partner organizations returning more than $576 million in calendar year 2013, the report noted.

“The IRS’s External Leads Program has more than doubled the amount of questionable refunds returned over the past three years, thus saving tax dollars,” said TIGTA Inspector General J. Russell George in a statement. “However, opportunities exist to improve the program.”

Since taking over the External Leads Program in January 2010, the IRS’s Wage and Investment Division has performed outreach in an effort to continuously increase the number of organizations participating in this program. Participation and the number of questionable refunds returned and the dollars associated with them have grown significantly.

However, the IRS is not always verifying leads in a timely manner, and the verification time frame goals differ significantly based on the lead type, according to the report. The goals do not take into consideration the burden on legitimate taxpayers whose refunds are being held until verification is completed.

In addition, the IRS inconsistently tracked the leads in multiple inventory systems, and the inventory systems did not provide key information such as how the lead was resolved, that is, whether the refund was confirmed as erroneously issued or legitimate.

TIGTA recommended that the IRS establish more consistent time frames to verify the leads it receives based on an analysis of the current and historical lead verification data and, once established, communicate the verification time frames with its external partners. The report also suggested the IRS develop a process to ensure that leads are verified within established time frames. The IRS should also consolidate the current four lead inventory tracking systems into a single tracking system and ensure that key information is captured as to how each lead is resolved, according to the report.

The IRS agreed with TIGTA’s recommendations. The IRS said it is evaluating the treatment streams and work processes associated with the various types of referrals received in the External Leads Program to identify appropriate time frames. The agency is also completing other systemic and procedural enhancements to improve the effectiveness of existing reporting capabilities in evaluating program quality and timeliness. In addition, the IRS is evaluating the feasibility and potential benefits of consolidating the four independent inventory tracking databases into one system.

“The IRS is committed to the proactive detection of fraudulent refund claims and preventing their payment from occurring,” wrote Debra Holland, commissioner of the IRS’s Wage and Investment Division, in response to the report. “Unfortunately, those individuals who commit fraud against the U.S. taxpayers continually modify their tactics to evade or avoid detection, which sometimes results in the issuance of erroneous refunds. Since 2010, the IRS has reached out to financial institutions, government entities, federal agencies, software providers and other stakeholders to develop processes whereby those partners may alert the IRS to suspected refund fraud, and return those funds to the Treasury when the suspected fraud is confirmed.”