Pension protocols

Hi, I'm hoping someone can clarify how pension works for English teachers (US citizens).

My boyfriend and I work together, but we have different salaries. We noticed the deductions for pension on our payslips were the same amount, and that amount is lower than either of our salaries. So, we asked why this was, since pension deductions should be 4.5% of our salary.

The Korean staff member who deals with all issues related to the foreign staff gave us the following explanation:

He said that's the way the pension office does things because pension is based on your previous year's salary. Since we didn't work for that school the previous year, they reported an average salary to the NPS. He said that at the end of the year, an adjustment would be made and assured us that our pension amount would be right in the end.

Can anyone verify this information?

Thanks in advance!