For the past few months, sales have already been hit by increasingly intense prices wars between T-Mobile, Sprint, Verizon, and AT&T. And that came amid dramatically slowing subscriber growth as the U.S. market reaches saturation, averaging more than 1.1 mobile devices per adult.

But an Internal Revenue Service move to crack down on identity theft and fraud could be taking a toll.

Last summer, the IRS said it would take longer to process 2017 payments related to the earned income tax credit and the additional child tax credit. That is now delaying payments to some 40 million people—payments they typically spend, at least in part, on upgrading a phone or signing up for new mobile service.

“Q1 thus far is going to be an interesting quarter to keep an eye on,” T-Mobile CEO John Legere said during a call with analysts on Tuesday. “We all know that tax season is somewhat delayed, and this is going to be a very rear-end-loaded quarter.

“They always start slow,” Legere added. “But there’s a tax season question, and so far there’s an awful lot to see in Q1, and I would assume that the rest of the industry sees that as well.”

Wall Street didn’t need to hear any more bad news. T-Mobile’s stock price, which had jumped 3% to $62.84 on the company’s fourth quarter earnings report, quickly dropped as low as $59.80 after Legere’s comments.

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Investors had been pleased with T-Mobile’s results up until that point on the analyst call. T-Mobile said it brought in revenue of $10.2 billion, up 23% from the fourth quarter of 2015 and more than the $9.8 billion analysts expected. Earnings per share of 45 cents beat last year’s result by 11 cents and exceeded Wall Street’s forecast of 30 cents a share.

After the initial observation, Legere got more questions from the analysts about the impact from tax season, and he backed down a bit.

“I’m referring to nothing more that what is written in the media that the season associated with tax refunds seems to be somewhat slow,” he said.

That helped the stock recover somewhat. The shares were trading at $60.98, virtually unchanged from Monday’s close, in afternoon activity.

The refund delay could simply push sales into the second quarter, resulting in no real losses for the industry, T-Mobile chief operating officer Mike Sievert told analysts later.

“Some of the expected bump in business that we normally get around tax refunds could spill into Q2 as well,” Sievert said. “The fact that tax season is a little bit delayed is a little bit atypical. So we’ll see how it all unfolds, but it’s looking like it’s going to be a back end heavy quarter for the industry.”

Even amid the tax concerns, T-Mobile (TMUS) executives said they are still pulling in the lion’s share of new subscribers. The carrier added more subscribers than it three main competitors combined over the past three years. And in the first quarter so far, the company is seeing almost two people switching to T-Mobile for each customer that switches out. T-Mobile is competing “as well as we ever have, or better,” Sievert said.

Legere also addressed the increasing price competition, with Verizon (VZ) surprising the industry on Sunday with a new unlimited data plan starting at $80 and Sprint (S) cutting the price of its unlimited plan temporarily to $90 for up to five lines.

Verizon’s move, in Legere’s view, represented a concession that consumers no longer would pay more for its perceived better mobile network. “They finally agree their network advantage is over,” he said. “Welcome to the game Verizon. Let’s compete on price.”

As for Sprint, Legere remarked: “You’ve clearly seen some moves that can only be deemed desperation.”