Pop diva Toni Braxton has been battling health problems for the last few years -- and she might need all her strength to pack up her stuff and move ... cause the bank is coming after her home.

According to documents filed last month, Braxton has defaulted on her mortgage payments -- and now Bank of America is looking to foreclose. They claim she owes $12,503.20 on a place in Century City, Calif.

Toni closed down her Vegas gig a few years back -- she may want to start it up again ... quick.