A new report from the state comptroller finds Mayor Michael Bloomberg's $68.7 billion proposed budget for fiscal year 2013 relies heavily on resources that will not be available in 2014 and later years.
The mayor's budget uses $4 billion in so-called "nonrecurring resources," according to comptroller Thomas DiNapoli. The resources include $1.6 billion in surplus funds from fiscal year 2012 and $1 billion from the anticipated sale of 2,000 taxi medallions.
Legal challenges and the process of getting state approval could hamper the sale of medallions, DiNapoli outlined.
He also cited fluctuating Wall Street profits as a cause for concern.
The report alluded to a recent $2 billion trading loss at JP Morgan Chase, saying it may be a sign that future profits from the securities industry will be lower than forecast.
DiNapoli is recommending that the city develop a contingency plan in case the funds are not fully realized.
The comptroller also says that the use of one-time funding sources means the city still faces sizeable gaps in future budgets.
A spokesman for the mayor said Mayor Bloomberg agrees with the overall argument and that balancing the budget starting in fiscal year 2014 will be more of a challenge.