AUGUSTA — State revenue for the fiscal year that ended June 30 exceeded projections, leaving Maine with a surplus of nearly $58 million.

Nearly half of that unanticipated income — just less than $28 million — came from a one-time spike in individual income tax revenue, according to preliminary calculations included in a monthly report from the state’s Office of Fiscal and Program Review.

The jump in income tax is the result of wealthy Mainers backloading their income into the last months of 2012, said Michael Allen, Maine’s associate commissioner for tax policy.

Because Bush-era tax cuts expired Jan. 1, 2013, and new taxes created by the federal Affordable Care Act were set to take effect, wealthier residents and businesses managed their finances to claim as much income in 2012 as they could to make it subject to more favorable federal rates, he said.

“People sold off assets, companies issued dividends or paid bonuses that may have normally occurred the next year,” he said. “A lot of income was shoved into 2012.”

General Fund revenue accounted for $46 million of the surplus, while appropriated but unspent money added another $6 million. Miscellaneous adjustments made up another $5.7 million.

Aside from the individual income tax spike, other major one-time sources of the surplus included nearly $9 million in unpredicted revenue through the estate tax, fueled largely by a single payment from one large estate, and an unexpected $4.8 million increase in projected income from unclaimed property.

But the surplus doesn’t mean lawmakers can spend more money however they choose; Maine law establishes how unanticipated revenue at the end of a fiscal year must be funneled into various accounts. Most of it — $42 million in this case — is dedicated to “budget stabilization,” essentially a rainy day fund to be used in case of a recession.

A total of $4.1 million will be put into a retirement reserve account. Another $4 million will be put into an account designed to eventually decrease the income tax rate. Lesser amounts are earmarked for other purposes.

Most would agree a year-end surplus is a good problem to have. But Rep. Peggy Rotundo, D-Lewiston, House chairwoman of the Legislature’s budget-writing Appropriations Committee, said she wished she’d known the state would see more money than expected before a deal was reached on the new biennial budget.

Had the additional money been planned for, lawmakers may have had more options in making tough financial decisions such as raising the sales, meals and lodging taxes or cutting municipal revenue sharing.

In his original budget proposal, Republican Gov. Paul LePage proposed a complete suspension of revenue sharing for the two-year budget cycle that began July 1. Amid howls of protest from municipal and school leaders, the Legislature approved the Appropriations Committee’s budget that restored about 65 percent of the $400 million in state revenue sharing that LePage had eliminated in his proposal.

While the $58 million surplus reflects revenue received by the state before the new budget’s revenue sharing changes took effect, it might have affected the way legislators approached planning for the new two-year budget, Rotundo said.

“As someone who led the charge for pushing as much restoration of revenue sharing as possible, we would have loved to have been able to use some of this money to fully restore revenue sharing,” Rotundo said.

If revenue continues to flow faster than expected, Democrats could attempt, as part of a supplemental budget, to restore the remainder of revenue sharing that was cut in the new biennial budget.

Republicans, on the other hand, would seek to roll back the temporary sales tax increase that lawmakers relied upon to balance the new biennial budget, according to House Minority Leader Ken Fredette, R-Newport.

“I would favor a supplemental budget that would eliminate the sales tax increase built into the biennial budget,” he wrote in an emailed statement. “Higher revenues shouldn’t be spent by the government, but should be returned to the taxpayers, and this proposal would do that.”