The phrase "dollar shortfall" refers to a situation where there is not enough money in dollars available or needed for something. It is a shortage or lack of dollars. Full definition
This makes a $ 1.5 billion dollar shortfall for the year in 2007. (insuranceproviders.com)
Twice in recent days he's said there could be a multi-billion dollar shortfall in the budget next year. (wamc.org)
For example, a teacher in Iowa, a state with strong fiscal health and a substantial surplus, recently discovered that her pension contributions were recently raised to cover a multi-billion dollar shortfall in the state's teacher pension fund. (teacherpensions.org)