The Ben Thanh-Tham Luong line is now scheduled to be "basically completed" in 2030 instead of 2026, with the official opening in 2032, according to a decision by Deputy Prime Minister Tran Luu Quang.
The decision was made to find time for a new consultant and extend loan agreements with foreign banks funding the project.
Initially planned for completion in 2016, the line, which runs 11 km between Districts 1 and 12, was pushed back to 2026 and has now been delayed again, with construction started last year.
HCMC Management Authority for Urban Railways (MAUR), which manages metro projects in the city, has failed to compensate families affected by the construction, citing disagreements with authorities in several local districts.
MAUR has also failed to renew an independent consultant contract for the project, causing delays in spending.
The line originally had a consortium of three German companies, one Swiss company and a Vietnamese company with agreements to provide the engineering, design and supervision of services.
The services cost nearly $52.4 million, funded by a non-refundable grant provided by German state-owned development bank KfW.
The agreement ended in March after both sides failed to agree on a renewal.
The group had begun work in 2012 but stopped in 2018 after a dispute over fees.
MAUR said it did not resume the agreement after the consultancy demanded nearly 29%, or 12.6 million euros, more than the original sum agreed. The two sides held several rounds of negotiations but failed to reach an agreement.
MAUR is now inviting bids for construction contractors to start work in 2025 and finish in five years.
The line's initial $1.3 billion price tag ballooned to $2.1 billion by the end of 2019 on rising material and construction costs.
The delay has led to the expiry of five contracts to borrow money for the project from KfW, the Asian Development Bank and the European Investment Bank. The city must now extend contracts with the banks.
Aside from line No.2, the first metro line – from District 1 to Thu Duc City – has also been delayed. Initially set for completion in 2018, it is currently set to be up and running by the end of this year.