RALEIGH, N.C. — North Carolina government’s top fiscal analysts have officially set a goal for the state’s rainy-day reserve fund that once met should help fill large shortfalls encountered during most recessions.

A law approved last year requires a set percentage of annual revenue growth be transferred to the reserve, which already has more than $1.8 billion. The law directs the state budget office and the legislature’s Fiscal Research Division to come up with an annual target.

That target is a percentage of the previous year’s revenues — meaning for now reaching the goal would require increasing the fund by roughly $700 million over time.

State Budget Director Charlie Perusse told legislators in a memo the target percentage may change over time as revenue data increase.