For those who file paper returns, refunds are expected to take four weeks to six weeks, said David R. Williams, the agency’s director of electronic tax administration.

“We believe e-file is safe and secure, and we work with the tax software industry to make sure it stays that way,’’ Williams said.

One group still will need to file paper forms: those taking advantage of expanded home buyer tax credits approved by Congress in November. Congress required documentation to claim the credits, so those returns must be done on paper, Williams said.

Under the program, buyers who have owned their current homes at least five years would be eligible, subject to income limits, for tax credits of up to $6,500. First-time home buyers or people who haven’t owned homes in the previous three years could get up to $8,000.