New York Real Property Tax Law Section 924-A - Interest rate on late payment of taxes and delinquencies.

 924-a. Interest rate on late payment of taxes and delinquencies.  1.
  The  amount  of  interest  to  be  added on all taxes received after the
  interest free period and all delinquent taxes shall be  one-twelfth  the
  rate  of  interest as determined pursuant to subdivision two or two-a of
  this section rounded to the nearest one-hundredth of a percentage point,
  except as otherwise provided by a general or special law, or a local law
  adopted by a city pursuant to the municipal home rule law or any special
  law. Such interest shall be added for each  month  or  fraction  thereof
  until such taxes are paid.
2.  The  rate  of interest applicable to the third calendar quarter of
  each year, as set by the commissioner of taxation and  finance  pursuant
  to  subparagraph  (A)  of paragraph two of subsection (j) of section six
  hundred ninety-seven of the tax law,  shall  be  the  rate  of  interest
  applicable  to  unpaid real property taxes for purposes of this section.
  Such commissioner shall set such rate on or before the fifteenth day  of
  July  in each year. Such rate shall be effective for all warrants issued
  for a collection  period  commencing  on  or  after  the  first  day  of
  September  next  succeeding  the  date  the  rate  of  interest  is set.
  Provided, however, the rate of interest prescribed by  this  subdivision
  shall  in  no  event  be  less  than  twelve  per  centum per annum. The
  commissioner shall inform each affected municipality of  any  change  in
  the rate established pursuant to this subdivision.
2-a.  Notwithstanding  the  provisions  of  subdivision  two  of  this
  section, the Schenectady county legislature may adopt, amend or repeal a
  local law to prescribe the rate of interest at fifteen  per  centum  per
  annum.
3.  In  any  case  where  a  county,  by local law, has authorized the
  collection of such property taxes in installments, such  local  law  may
  establish  an  interest  rate  in  such  local  law  to  be paid in such
  installments which is less  than  the  interest  rate  provided  for  in
  subdivision two of this section. Where such local law does not establish
  such  a  lower  interest rate, such rate shall be the rate determined in
  accordance with subdivision two of this section.

Last modified: February 3, 2019