Proprietor advance payment for services to be rendered. TAX CALCULATION - please advice

A proprietor usually gets advance payment once in 3 months for his services rendered like below

FY 2020-2021

Rs X in April 5th 2020 for services to be rendered from April 2020 to June 2020

Rs X in July 5th 2020 for services to be rendered from July 2020 to September 2020

Rs X in October 5th 2020 for services to be rendered from October 2020 to December 2020

Rs X in January 5th 2021 for services to be rendered from January 2021 to March 2021

Income = 4X

FY 2021-2022

Rs X in March 5th 2021 for services to be rendered from April 2021 to June 2021

Rs X in July 5th 2021 for services to be rendered from July 2021 to September 2021

Rs X in October 5th 2021 for services to be rendered from October 2021 to December 2021

Rs X in January 5th 2022 for services to be rendered from January 2022 to March 2022

Income 4X

FY 2022-2023

The problem: He received payment of Rs X exactly in March 31st 2022 for advance services to be performed from April 2022 to June 2022

Case1:

Income in FY 2021-2022 is 4X

Income in FY 2022-2023 is 4X

Case2:

Income in FY 2021-2022 is 5X

Income in FY 2022-2023 is 3X

Question: So how will tax be computed? case1 or case2? If it is case2 tax liability becomes huge

I know there is  a form 10E 89(1) for salaried persons to declare advance salary but is there a form like that for proprietor? 

Thanks 

Shanthi