Query regarding filing of income tax return

I have a salary income of Rs. 40 lakhs with a TDS of Rs. 9 lakhs which is reflecting in my form 26AS. However, It is stipulated in my employment agreement that if I'll change my job then I will have to return last quarter's salary of Rs. 6 lakhs which I have returned in the succeeding F.Y. i.e.2021-22.

So my query is that how much proportion of my salary i.e. 40lakhs is taxable in F.Y.2020-21.

Kindly resolve my issue asap.