Services were due to begin running from Bull Street to Stephenson Street on Sunday, 22 may.
However, the delay follows extensive safety checks by Centro, the delivery arm of the West Midlands Integrated Transport Authority.
The 1.2km scheme is part of a £128 million project which involves the introduction of a new fleet of trams, a refurbished depot at Wednesbury and a new stop at Snow Hill station.
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Overall, around 1,300 jobs are expected to be created with more than £50m generated for the West Midlands economy.
Centro's Midland Metro programme director Phil Hewitt, said: "It is bitterly disappointing as everything else is in place and ready to go but, as we have said right from the start, safety is paramount.
"A stringent testing programme has identified minor anomalies in some of the track alignment which need to be addressed.
"These are exactly the sort of issues the tests were designed to identify.
"However remedial work is relatively straightforward. Once that is complete, on-street driver training can begin and we will soon have passenger services running."
(LM)
