A donor has given us quite a lot over the years. What is the substantial-contributor threshold?
There are two tests, and meeting either one is enough.
A person is covered if their contribution during the relevant tax year exceeds Rs. 1 lakh, or their total contribution up to the end of that tax year exceeds Rs. 10 lakh.
So track both the current-year and the cumulative amount for each donor.
Source: Income-tax Act, 2025 - section 355(h)(ii).