Average tax refunds rebounded after a weak start to the tax-filing season, according to Internal Revenue Service data released Thursday that was highlighted by Treasury Secretary Steven Mnuchin.

The average tax refund was $3,143 through Feb. 22, a 1.3% increase from the same period last year. Before that, average tax refunds had been running behind last year’s pace. Through Feb. 22, about 81% of tax returns that have been processed are yielding refunds, nearly identical to last year.

The...