Premier League midfielder agrees month deal with Blues
The 29-year-old midfielder will train with Blues for the first time Friday morning and will be in contention for the squad to face Peterborough at the weekend.
The paperwork has yet to be completed but should be done in time for the former Republic of Ireland U21 international to feature at London Road.
Tabb started his career at Brentford and went on to make more than 150 appearances for the club before joining Coventry in 2006.
He became a big favourite with the Sky Blues fans at the Ricoh Arena in his three years there before heading to Reading.
He has clocked up over a century of appearances for the Royals and helped them to promotion to the Premier League last season.
Capped 10 times for the Republic of Ireland U21s, he has featured 12 times for Reading in the top flight this term.