I would like to transfer my PF from A company to B company provided both the companies have proper digital signatures in the EPFO website. But the issue is, my previous company has been closed 6 months back.
Can we change the last sentence to the following, and which is preferred when?
my previous company has been closed 6 months back.
This doesn't really work. It would make more sense to say "has been closed for 6 months."
my previous company closed 6 months back.
This means that the company is out of business. 6 months ago, it went from being a normal company to one that is closed forever. This seems like the one you are looking for.
my previous company was closed 6 months back.
This means that the company was in a closed state 6 months ago, but doesn't necessarily imply that it is closed right now. However, you could still use this to say that the company is closed permanently.
my previous company got closed 6 months back.
This implies that the company was shut down by an external source. The company didn't close itself, but it got closed (by someone/something). It also means the company is closed permanently.