The Championship strugglers are hoping to complete the deal on Friday to enable the midfielder to be available for their clash with Peterborough on Saturday.
The 29-year-old has found first-team opportunites hard to come by this season, making just 12 appearances for the Royals.
Reading boss Brian McDermott signed midfield duo Daniel Carrico and Hope Akpan in January, pushing Tabb further down the pecking order.
Shortly after the signings, McDermott admitted he would not stand in Tabb's way if he wanted to leave the Premier League club.
"Make no mistake, I rate Jay very highly," he said. "At this moment in time he's not been offered a contract so I'm trying to do right by him, it's a fine balance.
"We've signed Hope and Daniel, we have five or six midfield players, if he's not in our 18 every week and if he wants to go and play I'll do right by him."
Ipswich are currently just four points clear of the relegation zone, and manager Mick McCarthy has targeted Tabb to replace Lee Martin as he begins a three-match suspension.