Connecticut is once again coming up short on cash, and its rainy-day fund is already strained.

About halfway into the budget year, sales and income tax revenues have come in about $208 million under projections. That comes even after lawmakers enacted deep spending cuts, raised fees on motor-vehicle registrations and required teachers to contribute more to their pensions to pass a two-year budget in a bruising process that took 10 months.

Shortfalls...