Kim Zolciak and Kroy Biermann are still beefing with a bank over their Georgia mansion ... and now the bank says it has every right to foreclose on the place to collect the money it’s owed.

According to new legal docs, obtained by TMZ, Truist Bank claims the couple defaulted on their mortgage … and now the bank has the right to foreclose on their mansion.

Kim and Kroy are going through a messy divorce, but they're still living inside the family residence ... remember, Kroy's got the primary bedroom and Kim has the nanny suite and basement.

Truist Bank says it's well aware of the divorce proceedings, but it claims that's not enough to block its foreclosure rights.

TMZ broke the story ... in October, Kim and Kroy asked a judge to stop the bank's foreclosure auction so they could sell it on their own ... and they've slashed the price on the estate to $5.5 million.

Truist Bank says it voluntarily delayed the auction in November ... but Kim and Kroy haven't been able to sell it themselves, and now the bank is apparently getting impatient and intends to exercise its foreclosure rights so it can collect on the debt.

Meanwhile, Kim and Kroy remain at each other's throats over their finances and divorce proceedings ... that is, when they're not banging.