The city’s finance department fined property owners $27.1 million for not complying with income and expense form reporting requirements, The Post has learned.

While the letters were mailed in early March, many owners are just realizing that the fines have been tacked onto their tax bills.

According to the finance department, 78,988 properties were required to file 2010 numbers in September 2011, but 7,095 did not do so.

The $27.1 million in fines for these owners represent 0.75 percent of the assessed value for first-time non-filers, and 1.5 percent for repeat offenders. Current law allows for greater fines.

The real property and income expense statements (RPIEs) have been part of the city’s assessment strategy since they were implemented by city law in 1986. Most income-producing properties with a final assessed value of over $40,000 are required to file on a yearly basis by Sept. 1, although the finance department would rather have the deadline be in June.

While there are permitted exclusions — including buildings with 10 or fewer residential apartments or six or fewer apartments and one store — these owners must still file a form and check a box stating why they don’t have to file.

The new figures show that fining the non-filers for the first time in nearly two decades is also leading to more compliance. Of the 79,974 properties required to file a 2009 RPIE, 26,378 did not do so — a 67 percent rate of compliance.

For 2012, when the finance department warned that fines would be imposed on 80,370 properties, compliance leaped to 89 percent. The 8,465 non-filers were fined $3.2 million based on an even smaller percentage of their assessed value.

The penalties were kept relatively low as this is the first year they were imposed, said a finance spokesman.

The number of non-filers for September 2012 has not been tallied and no fines have been imposed on the properties identified in a list dated Feb. 7, 2013. Fines may be imposed later.

The majority of the buildings on the lists have low assessed values — generally less than $1 million — but several large value properties popped up.

The Palace Hotel was purchased in the middle of the reporting year and an executive with the ownership was unaware of the form or requirement.

A large office building net leased by Credit Suisse also missed the filing this year as it fell through the cracks, sources said. Neither building appeared on last year’s list.