1. Debt cannot be solved by telephone, letter and other communication methods. If the bank calls several times for dunning, but the customer never answers, and there is no reply to the email or letter, the bank may choose to take legal measures to solve the problem of overdue repayment.

second, the debt cannot be solved by collection measures. After a period of overdue, the bank will take internal collection measures, including reminding customers to repay by phone, text message, letter, etc. If these collection measures are ineffective, the bank may choose legal channels to recover debts.

third, the amount of debt is large and the other party has the ability to repay. If the overdue amount reaches more than 1,, and the bank judges that the customer has repayment ability (such as stable job and fixed income), but the customer still refuses to repay or delays repayment, the bank may recover the debt through litigation.

to sum up, banks may choose to sue to recover their debts when the overdue amount is more than 1, months, which cannot be solved by communication, the collection measures are ineffective, and the customers refuse to repay.

Extended information:

According to the Contract Law of the People's Republic of China and the Tort Liability Law of the People's Republic of China, the borrower's overdue repayment is a breach of contract, and the bank, as a creditor, has the right to take legal measures to safeguard its own rights and interests. The ways to sue overdue debts include filing a civil lawsuit and applying for property preservation measures.

please note that the above information is for reference only, and the specific laws shall be subject to local laws and regulations and bank regulations.

supplementary information: assuming that the customer is unable to repay, the bank may choose other solutions after taking appropriate collection measures, such as negotiating with the debtor to reduce the debt amount or making repayment plans. Banks may weigh the amount of debt, customer credit history and recovery costs to decide whether to sue immediately. The specific situation in this regard may be different because of the policies and operational procedures of different banks.