What's the noun for short-fall? Here's the word you're looking for.
shortfall
An instance of not meeting a quota, debt, or monthly payment on a debt or other obligation, or of having an insufficient amount to cover such obligations.
The amount by which a quota, debt, or monthly payment on a debt or other obligation is missed; the difference between the actual quota or debt and the lesser amount available to pay such obligations.
“The short-fall was made more acute by the fact that the areas in the west of the province had richer soils, and were more abundantly irrigated.”
“Immigrants have swelled the ranks of young age groups as the baby bust has aged, filling in a short-fall in demand created by the baby bust, according to Fannie Mae's Berson.”