Can income accrued be declared, using Mercantile accounting, without invoice?

Dinesh (CS) (36 Points)

15 July 2023  

Business/Profession: Freelancing in Upwork.

Type of income calculation: Presumptive/44ADA

A client worked without any formal agreement in Upwork for  a foreign company from Jan 2023 to April 2023. But invoice is generated only on July 2023 and paid fully and TDS deducted by Upwork for FY24.  Is it possible to declare 3/4th of this income in FY23 ITR return, using Mercantile type of accounting,  since the income is accrued only during FY23? If so, what documents are required for this? The only evidence that they worked during this period is the chat history between the client and their company. Note that client is not required to maintain any books of accounts as they're filing under 44ADA.