Ahahahaha... since I can't play that much and have gotten utterly bored with bug farming the island, I think I have 1,100,000 (always has to be even batches of 100,000 that I deposit) since I took out 800,000 to buy the throne.
But I have a fully upgraded house so I'd have more in the bank if I hadn't plough my money into that and the fixed PWPs.
About 12.5 million! I wasn't trying that hard at first but these last two turnip weeks have been good to me. Whenever I have a buncha money on me I tend to deposit it and then not touch it unless I need to dump like 500k on some dlc XD
I have 20 million in the mayor's account and I'm working on getting all of my other characters up to 20 milllion also. Intrest topsout at 99,999 (which is what you get from 20 million). So if you have multiple characters, having over 20 million in the bank for one character but less for the others doesn't get you anything (other than the Mailman Hat & ABD).