Is my monthly income with CPF contribution calculated as 3888 SGD times 20%?

To determine if your HDB loan will be affected, you need to consider your gross monthly income, not the income after CPF deductions. However, since you mentioned your monthly income after CPF is 3888 SGD, let's clarify the calculation based on your gross income.

Your gross monthly income is 4666 SGD. The Total Debt Servicing Ratio (TDSR) and Mortgage Servicing Ratio (MSR) are key here. For HDB loans, the MSR should not exceed 30% of your gross monthly income.

Given your gross monthly income of 4666 SGD:
- Maximum monthly repayment for HDB loan: 4666 * 0.30 = 1399.8 SGD

If your other debt obligations, including the 471 SGD you mentioned, do not exceed this limit when combined with your HDB loan repayments, you should not face a cut in your HDB loan.

To check, you would need to sum up all your monthly debt repayments and ensure they do not exceed 1399.8 SGD. If the total is within this limit, your HDB loan should not be affected.