After seven years, playing as a team regular, Kaltsas decided to leave the club and join Panathinaikos on a free transfer, as he didn't renew his contract which was set to expire on 30 June 2015.
The first was when a proposal came from Segunda División club Hércules CF of Kike Hernández[citation needed] for a loan of six months, giving Veria an amount of €50,000.
The announcement of the acquisition from Greek giants Panathinaikos just a few hours before a Super League game against Panetolikos, provoked mixed feelings to Veria's fans.
[4] On 11 January 2016, Kaltsas made an excellent appearance along with an early goal in the second half, helping his club to escape with a 2–0 win against Kalloni and climbed at the third Super League position.
The 26-year-old former player of Veria scored five goals in 27 appearances with the Greens during 2015–16 season, but was not in Italian manager Andrea Stramaccioni's current plans.