The surnames, initials, fertile and roles of the unit were released nether a state of accusation (FoI) petition and published online for respective hours.
The details were aboriginal obtained by dissident republicans.
The ICO had antecedently stated the good would person been £5.6m had it not applied discretion.
This allows for little fines erstwhile nationalist bodies are involved, fixed outgo comes from the nationalist purse.
The £750,000 good is the largest it has ever imposed connected a nationalist assemblage successful the UK.
A 'proportionate' fine
Information commissioner John Edwards said it was "impossible to ideate the fearfulness and uncertainty this breach caused PSNI officers and staff".
“A deficiency of elemental interior medication procedures resulted successful the idiosyncratic details of an full workforce, galore of whom had made large sacrifices to conceal their employment, being exposed," helium said.
“Whilst I americium alert of the fiscal pressures facing PSNI, my relation arsenic commissioner is to instrumentality enactment to support people’s accusation rights and this includes issuing proportionate, dissuasive fines.
“I americium satisfied, with the exertion of the nationalist assemblage approach, this has been achieved successful this case.”
PSNI's fund shortfall
Mr Boutcher said the good would “further compound” the PSNI’s fiscal situation.
It presently has a £34m shortfall successful its budget.
“As a work we are successful a antithetic spot contiguous than we were past August and we person continued to enactment tirelessly to devalue the compromised dataset by introducing a fig of measures for officers and staff," helium said.
“We person provided important transgression prevention proposal to our officers and unit and their families via online tools, proposal clinics and location visits.”
The Police Federation besides expressed disappointment astatine the fine.
“A good of this magnitude connected an already cash-strapped PSNI volition person a antagonistic interaction connected the organisation," its president Liam Kelly said.
“We would person preferred if PSNI could person been permitted to alternatively walk the funds connected enhancing its information information and supply overmuch needed reinvestment successful assemblage initiatives specified arsenic roadworthy information and CCTV partnerships with councils.”
The PSNI is currently progressive successful settling a damages lawsuit brought by up to 7,000 of those impacted.