For a corporation that is nonprofit, the amount of prudent reserve it should keep is not an easy question to answer; each nonprofit needs to determine how much it needs to keep on the books.

"Latest figures from the NCVO estimate that reserves held by UK charities are collectively worth around £49bn, which equates to 15 months of spending.

"It’s not an insignificant sum. But while the amount held per organisation varies, the question of how much charities should ideally have in reserve is a difficult one to answer. Recently, one contributor to a live Q&A described applying to the same funder in successive years; the charity was told it either had too much in reserve (12 months), and should finance the work itself, or that there were concerns about sustainability (when they had seven months’ worth in the bank)."--Saba Salman, The Guardian