Three weeks into tax season, Americans' tax refunds are shrinking. The average refund issued through Feb. 15 was 16 percent smaller than this time last year, according to data released by the Internal Revenue Service. The average refund so far this year is $2,640, down from $3,169 in 2018.

The number of taxpayers getting refunds is also sharply lower compared with last year -- down more than 26 percent, though the number of tax returns processed was down by only 6.6 percent.

For now, experts caution against reading too much into the IRS figures, which can swing dramatically week to week. About 28 million tax refunds are being delayed until at least Feb. 27 thanks to laws around the Earned Income Tax Credit, which is claimed by lower-income taxpayers, and the Child Tax Credit, which the 2017 tax reform dramatically expanded.

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"[T]he slow start to the tax refund season may not be indicative of what's to come in the next few weeks. Last year's data shows that the largest surge has tended to come at the end of February," analysts at Morgan Stanley wrote in a note.

Smaller refunds also don't mean that someone paid more tax. Most Americans got a tax cut from the 2017 tax reform, according to the Tax Policy Center.

"We see clients getting smaller refunds, but when people compare the actual tax they paid, it's sometimes thousands of dollars lower," said Caleb Paddock, a certified financial planner in Colorado.

Still, the refund is an important cash infusion for many American households. For most, it's the largest lump payment they receive all year. For that reason, some economists are concerned about the effect that smaller refunds could have on consumer spending.