The company reported an adjusted loss of 55 cents per share, two cents wider than anticipated. Revenue also fell below forecasts to $125 million versus the $133 million estimate.
The stock was down 12 percent on heavy volume of nearly 6 million shares by late-morning. The stock later recovered some of its losses, but still ended the day down 10.5 percent.
This was H&R Block's third loss in the last four quarters amid changes to the company's balance sheets after the sale of its bank business to a unit of BofI Holding.
While the tax preparer did not provide any guidance, CEO Bill Cobb offered a positive outlook to investors. "Because of the highly seasonal nature of our business, the fiscal first quarter is not indicative of our full year results," Cobb said in a statement.
"That said, all of the company's efforts remain laser-focused on executing a successful tax season," Cobb added.
In April, H&R Block said it was laying off 250 workers during a disappointing tax season. The company says it is on target to carry out these cost-reduction plans, saying "the majority of our planned reductions will occur after the first quarter."
Wednesday marked the H&R Block's third worst session of the year. 2016 has not been kind to Block, with shares down more than 36 percent year-to-date. If shares continue to sell off, this could mark H&R Block's worst year since 2010 when it fell 47 percent.
HRB year to date Source: FactSet
-CNBC's Chris Hayes contributed to this report