Income tax on unrealized export bill

Anish (Owner)     21 December 2020

I have a unrealized export bill against a shipping bill of Dec 2019 amounting USD 18459. In that case would like to know the income tax implication on that. If I have to pay the tax on profit (would be) then will the shipping bill exchange rate should be considered to get the INR value in order to pay income tax for FY 2019 20? As actual amount can only be ascertained after receiving the payment from overseas buyer depending on the prevailing exchange rate in future. Would request someone to kindly provide an advice on the issue.