Comparisons reflect the fact that this year's filing kicked off on time, while the acceptance of returns was delayed in 2014 so that there was only one day of filing in January. However, the growth of return filings by paid tax preparers lagged far behind self-prepared all during last season, even after 2014 filings caught up with 2013.

There were 5.9 million returns efiled by professionals, an increase of 39.1 percent from the 4.2 million that group filed at same point the 2014 tax season There were more self-prepared returns but the 7.5 million filed were up 20.4 percent from 6.2 million in the comparable period a year earlier.

The IRS did not discuss reasons for the changes, beyond noting last year's delay. However, there have been expectations that the advent of requirements of the Affordable Care Act would drive some do-it-yourselfers to professionals.

The IRS received slightly more than 14 million returns total for the period, an increase of 25.6 percent with just under 13.9 million processed, up 25.9 percent.

Notably, direct deposit refunds boomed with 7.3 million issued, up 96.8 percent from 3.7 million during the same period in 2014. The dollar amounts refunded naturally rose, hitting $26.2 billion, an increase of 117.5 percent from just over $12 billion.

Overall, there were 7.6 million refunds issued, up 97.9 percent. However, the average refund of $3,539 rose only 10 percent from the prior year.