Many of us find the Internal Revenue Service’s income tax return pretty darn difficult to figure out, which is why companies like H&R Block exist — ostensibly, to help customers maneuver the complicated forms and get them a nice tax refund if possible. But it seems H&R finds those forms confusing, too.

The IRS told MarketWatch that the biggest tax preparer in the nation bungled more than 600,000 returns, causing refund delays of up to six weeks. Ouch.

H&R apparently biffed when filing Form 8863, used to claim educational credits, accidentally leaving a mandatory field blank. That’s resulted in a delay for about 10% of the 6.6 million people who filed a tax return containing that form, said an IRS spokeswoman. She says the IRS is hoping to reduce refund wait time but some taxpayers will have to wait a bit.

As for H&R Block, it confirms there was an issue with forms filed before Feb. 22, citing a change in the way the IRS processes certain yes or no questions on the form. It used to be acceptable to leave a field blank to indicate “no,” but now preparers must enter an “N.”

The company says it’s working with the IRS to fix errors but hasn’t said how it’ll go about that or how long it will take for refunds to arrive.

H&R Block snafu delays 600,000 refunds [MarketWatch]

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