The Internal Revenue Service will begin accepting tax returns on paper and via the internet on Jan. 31.

The IRS had hoped to open the tax season in mid January, but the 16-day government shutdown in October forced the agency to put modifications to its computer systems on hold, and pushed opening day back, an IRS news release says.

“Our teams have been working hard throughout the fall to prepare for the upcoming tax season,” IRS Acting Commissioner Danny Werfel said in the release. “The late January opening gives us enough time to get things right with our programming, testing and systems validation. It’s a complex process, and our bottom-line goal is to provide a smooth filing and refund process for the nation’s taxpayers.”

According to the release, the shutdown came as the IRS was ramping up annual updates to it’s more than 50 tax systems to prepare for the nearly 150 million tax returns filed each year.

The release also pushed the IRS’ electronic tax filing services, free file and e-file.

Both services are run by private contractors and not likely to be impacted by the kinds of difficulties that troubled the launch of healcare.gov, said Raphael Tulino, an IRS spokesman.

“I can guarantee you that we’ll open the system on January 31, and in all the years I’ve been here I’ve never seen it not work,” Tulino said. “There’s nothing on the IRS website that I would see that would have any hinderance to return filing.”

The IRS’s website is http://www.irs.gov.