In Anhui Chizhou, the social security base of 10400 yuan approximately corresponds to the 150% grade. Here's the detailed analysis:

1. Determination of social security base grades: Generally, social security base grades are set as percentages of the local average wage of employees in urban units on a full - scale basis, typically including grades such as 60%, 70%, 80%, 90%, 100%, 150%, 200%, 250%, and 300%.

2. Calculation basis: In 2024, the upper limit of the monthly payment base for social insurance in the whole province of Anhui is 21133 yuan, and the lower limit is 4227 yuan, based on the average wage of employees in urban units on a full - scale basis in 2023, which is 7044.38 yuan/month.

3. Specific calculation for 10400 yuan:

• First, assume the average wage is ​
  x=7044.38
  yuan.

• Let the grade be ​
  y
  . We know that the social security base = ​
  x×y
  .

• Substitute the values, ​
  =7044.38×y
  .

• Solve for ​
  y
  , ​
  y=7044.38​≈1.476
  , which is approximately 150%.

When choosing a social security base grade, it is advisable to comprehensively consider personal economic conditions and future pension expectations. Higher - grade payments result in more pension benefits in the future but also entail higher current costs.