Haringey Borough Council said a campaign to halve council tax for volunteer police officers is pointless as the deadline for changes has passed.
Earlier this week, Liberal Democrat Lynne Featherstone, the MP for Hornsey and Wood Green, called on the authority to give Special Constables a 50 per cent tax break.
She said the scheme would reward existing special constables and encourage more people to volunteer and help the police fight crime.
However, according to the council, it is required by the Government to set out any revisions to its Council Tax Reduction Scheme by January 31 each year.
The authority says it agreed its scheme for 2014/15 on November 18, 2013, and it cannot now be legally amended.
Councillor Joe Goldberg, cabinet member for finance, said: “We’re proud to support all our police officers, PCSOs and special constables, whose dedicated work has led to crime rates in Haringey continuing to fall.
“We also know from our consultation with residents that they have real concerns about cuts to local police, which is why our budget proposals include setting aside resources for match-funding new officer posts to bolster our neighbourhood police teams.”
He added: “I’m disappointed the Liberal Democrats did not propose this idea when Haringey’s scheme was passed in November.”
Unlike Police Community Support Officers, special constables have the same powers and responsibilities as regular police officers.
They spend up to 16 hours a month volunteering with the police - all without pay - in order to help make our communities safer.