Year of allowance of expenditure u/s 40(a)(i)?

anuj agarwal (29 Points)

06 July 2020  
Sir i have a query in section 40(a)(i) as mentioned below, please help me to solve it :
1. As per section 40(a)(i) any sum is disallowed if
*Tds is not deducted or
*After deduction, has not been paid on or before the due date specified in section 139(1)
2. And as per first proviso to section 40(a)(i) deduction will be allowed in any the previous year in which such tax has been paid.
2. But as per second proviso to section 40(a)(i) assessee will not deemed to be in default if resident furnish his return of income including the income which was liable for tax deduction under chapter viia and
It shall be deemed that assessee has *deducted* and *paid* the tax on the date of furnishing of the return of income
Now my question is that:
Suppose an assessee paid a sum to non resident without deducting TDS in P.y. 2020
And non resident furnishes aforesaid income in his return of income before due date u/s 139
In which year expenditure will be allowed to the assessee and why?