Hundreds of thousands of taxpayers may have to wait an extra six weeks to receive their tax refunds due to filing errors, the IRS said Tuesday.

The IRS said 10%, or more than 600,000, of the 6.6 million returns claiming education credits it has received so far this tax season were improperly filed by tax software providers. As a result, those refunds could be delayed for as long as six weeks.

While the IRS didn't place blame on specific companies, tax preparation firm H&R Block (HRB) acknowledged that it encountered issues filing returns containing Form 8863 -- which is used to claim education credits -- before Feb. 22 because of changes the IRS made to the way it processes the form.

An H&R Block spokesman said that any problems have now been fixed and that it is working with the IRS to make sure refunds are provided as quickly as possible. It did not say whether it will reimburse filing fees for impacted taxpayers.

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This is the second delay for taxpayers claiming education credits since the IRS didn't even begin accepting returns containing Form 8863 until Feb. 14.

Meanwhile, another major tax software provider is having problems of its own -- though not on the federal level. The Minnesota Department of Revenue recently warned the state's residents not to use Intuit products like TurboTax to file their state taxes because of problems with its software that caused returns to be filed inaccurately.

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TurboTax said software glitches impacted around 10,000 Minnesota taxpayers and that all issues have now been resolved.

To check the status of your refund, use the "Where's My Refund" tool on the IRS website.