Changes in methodology resulted in inflated property tax bills for a number of homeowners around the city, according to a new audit from City Comptroller John Liu.

The audit found the city’s finance department changed its methodology prior to the 2011 fiscal year without warning homeowners.

In Queens, close to a third of all large co-op buildings rose by more than 50 percent in property value as a result.

In addition, the audit says, in helping set market value, the city used comparisons with sometimes inappropriate properties, like those in a different end of the borough.

Liu also found a $4.3 million software system used to help calculate property values was implemented three years behind schedule.

NY1 has reached out to the city’s finance department for comment.