Hennepin County remains on track to pay off its Target Field debt a decade earlier than expected, officials said this week.

Construction of the $555 million ballpark included $350 million in funding from the county, plus private funding by the Pohlad family, owner of the Twins. The county planned to pay it off over 30 years, or by 2037, but now expects to pay the debt by 2027.

Excess revenue from the ballpark sales tax, plus lower interest rates, have helped the county save money and pay off bonds sooner than expected.

An early payoff on the debt would mean that taxpayers could see an early end to the sales tax, which amounts to 3 cents on every $20 spent.

The county invested $350 million in the construction of Target Field with proceeds from three bonds. Those bonds are payable solely from the 0.15 percent ballpark sales tax imposed in 2006. To date, the county has paid $79.2 million of the bonds early. Favorable interest rates, as well as the early payments and shortening the debt, have resulted in more than $150 million in savings, officials said.

The county paid off one of three series of bonds in November, 21 years sooner than the $75 million bond was initially due. And last week, the county refinanced $150 million in bonds, which could be paid off by 2032 — five years early.

The sales tax also funds extended library hours and the county’s Youth Sports Program. Since 2009, $19.6 million of youth sports grants have helped fund 373 projects to build or improve sports facilities and playgrounds.

In addition, funds provide sports equipment and improved access to swimming lessons throughout the county.

When the program ends, county officials estimate it will have funded $130 million for youth sports and library programs in the county’s suburbs and Minneapolis.