Natalie Mullis, right, chief economist, Colorado Legislative Council, answers questions from lawmakers regarding the state's budget and economic outlook in 2013.

(AP Photo/Brennan Linsley)

Colorado lawmakers may have to refund money to taxpayers sooner than they initially expected.

Refunds are a sign of Colorado's booming economy. But it also means lawmakers will be restricted in how much money they'll be able to keep and spend under Colorado's Taxpayer's Bill of Rights, also known as TABOR.

Gov. John Hickenlooper told CPR's "Colorado Matters" that voters will have to decide whether to take the refund or give the money back to the state to pay for essential services.

State economists giving lawmakers a quarterly revenue forecast Monday gave conflicting estimates whether refunds are required in the 2015 tax year. Legislative economists say no, but warn that the possibility exists.

Refunds wouldn’t be triggered if revenue is below the projection of the legislature’s chief economist, Natalie Mullis.

"That makes me very, very nervous," Mullis said. "Because basically what I’m telling you is I don’t know if we’ll have a TABOR surplus this year or not."

However, Gov. John Hickenlooper's economists predict the state will need to refund nearly $200 million next year because of revenue increases in the current budget year. Lawmakers weren't expecting refunds until the 2016 tax year.

TABOR requires refunds when revenue exceeds the combined rate of inflation and population growth.