Reverse senario for TDS carry forward

A is a commission agent. A collects goods from farmers, does some processing and supply to a company B. for that B pays commission to A.

A supplied all produce in the month of March 2019 i.e., in the FY18-19.

B ltd accepts the produce after QC. it may reject some of it. after accepting the produce in the month of April, May, June i.e., in the FY19-20, it calculates the commission and deducts TDS. by the time of ITR Due date, the commission and its calculation would be available for us.

for example, Actual Commission in FY18-19 is 20 lakhs and in FY19-20 is 13 lakhs

now following are the doubts.

1. in which year, A should declare the income. whether in FY18-19 or FY19-20?

2. if you opine that A should declare income in FY18-19 on Mercantile basis, there would be a mismatch between 26AS commission amount and actual commission amount in FY20-21. how can we deal with it?

3. if you opine that A should declare income in FY19-20 on cash basis, that means A should declare loss in FY18-19 (as allthe expenditure would be incurred in FY18-19) isn't it?

4. if ITR for FY18-19 is already filed (without the knowledge that B would deduct TDS in FY19-20) declaring 20 Lakhs with 40% profit on payment of tax

a. whether A should declare 13 Lakhs in FY19-20. And claim balance TDS as refund. (if this option is selected there would be mismatch in every year between Actual commission and commission as per 26AS)

b. Whether A should declare ‘Zero’ in FY19-20 and 13 Lakhs in FY20-21 And claim total TDS amount as refund.

c. is it okay if A, in FY19-20, declares 20 Lakhs and claims 20 lakhs that is already declared in previous year as bad debts (As those 20 lakhs were shown as receivable from B. so that there won’t be any difference in B’s ledger) claiming total TDS amount as refund. and declare 13 lakhs in FY20-21.

d. any other option, Please Specify.

Please advise in detail to avoid any unnecessary concentration from Dept.

(Note: TDS on Bank branch audits is like, banks deduct TDS in FY18-19 and we declare the income in FY19-20. Here, carry forward of TDS is allowed. But this case is reverse to it)

Thanks in Advance.