The city's largest taxpayer is making a bid to be the city's third largest taxpayer in a move that could cost the city $300,000 this year.

STAG IV Belfast LLC, owner of a 141-acre Route 3 parcel that is home to Bank of America and OnProcess Technology, has requested an abatement for nearly half of its 2016 taxes based on an assertion that the property is vastly overvalued by the city.

Last year, STAG IV was billed for $650,000 in taxes based on an assessed property value of $28.4 million.

The company is seeking roughly $300,000 back in the form of an abatement. That number would come from a reduction of roughly $13 million in the assessment, City Assessor Brent Martin said.

On April 18, Martin met with the City Council behind closed doors. Later, in open session, councilors approved spending up to $25,000 on outside help with the abatement request.

Speaking after the meeting, Martin said the request took him by surprise, arriving the day before the deadline. Additionally, the city has reduced the assessment of the STAG IV property twice since 2015.

That year, Martin, who had just been hired by the city, lowered the assessment to $33.2 million from $41 million based on the condition of the buildings, which he toured after several informal requests from representatives of STAG IV. Previously, the assessed value had not changed since 2009.

Last year, in response to a formal request from STAG IV, Martin lowered the value by another $5 million on grounds that two of the four buildings in the complex were vacant and a third was only partially occupied.

The latest request, if approved by the city, would bring the value of the property to $15.8 million, or third in the ranks of the city's top taxpayers behind neighboring athenahealth ($19.2 million) and Central Maine Power Co. ($17.2 million).