Conclusion: China Construction Bank's credit card installment interest calculation method is based on the principal of 20,000 yuan, the handling rate for each period is 0.6%, and the total principal and interest to be paid for each period is 120 yuan. When repaying in installments, the principal payable per period is 20,000 yuan divided by 24 periods, which is approximately 833.33 yuan. Adding a handling fee of 120 yuan per period, the total repayment amount is 953.33 yuan. The handling rates for different installments are different, for example, 0.70% for 3rd, 6th, and 10th installments, and 0.60% for 12th, 18th, and 24th installments.

The application process includes multiple channels such as mobile banking, WeChat official account, SMS, personal online banking, smart teller machines, ATMs, credit card websites, outlets, and telephone calls. Among them, the minimum application amount is RMB 300 and does not exceed 90% of the total billed consumption. The specific operating steps and conditions for consumption installment are described in detail in the introduction and process of consumption installment business of China Construction Bank.