Funds taken out of earnings to provide for anticipated future payments(noun)
WordNet. Princeton University. 2010.
Use "reserve fund" in a sentence
"By curtailing expenditure and enlarging the revenues, chiefly by working the salt-mines himself and by increasing the taxes without regard to the complaints of the powerless estates, the finances were not only brought into a better condition, but it was also possible to collect a reserve fund which, in spite of the unusually difficult conditions of the age, was never quite exhausted."