Section 1448-H. Imposition of tax

Notwithstanding any other provisions of
  law to the contrary, the county  of  Essex,  acting  through  its  local
  legislative  body, is hereby authorized and empowered to adopt and amend
  local laws imposing in such county a tax  on  each  conveyance  of  real
  property or interest therein when the consideration exceeds five hundred
  dollars,  at  the  rate  of  one dollar for each five hundred dollars or
  fractional part thereof. Such local law shall apply  to  any  conveyance
  occurring  on or after the first day of a month to be designated by such
  legislative body, which is not less than sixty days after the  enactment
  of  such local laws, but shall not apply to conveyances made on or after
  such date pursuant to binding written contracts entered  into  prior  to
  such  date,  provided  that  the  date  of execution of such contract is
  confirmed by independent evidence such as the recording of the contract,
  payment of a deposit or other facts and circumstances as  determined  by
  the treasurer.