The Tory-run authority's cabinet was told to think again by the council's scrutiny committee after approving the move last month.
But members voted unnaimously on Tuesday night (January 18) to turn down pleas to cut the fee because cash is already earmarked for other services.
Nene Valley ward councillor, Phil Larratt, Cabinet portfolio holder for Climate, Transport, Highways and Waste Services, warned: "We have to look at the budget as a whole and we've put a lot of things in there that we want to restore such as highways services, HS2 marshalls .. things that we desperately need.
"We are investing in services, improving the standard of street sweeping in South Northamptonshire, and we will continue to do so.
"We need the income, unfortunately."
The subscription scheme — the same as one operating in Northampton since 2020 — is expected to raise around £800,000 in revenue.
Council officers estimated that would turn into a £1million deficit if the charge was lowered to £30.
Daventry residents already pay the equivalent of £42 a year for garden waste collections.
But the change means residents in the former South Northamptonshire District Council area will need to pay extra for the first time from April after having green waste collections provided as part of regular services paid for out of their council tax.
A group of independent and opposition councillors prompted the scrutiny committee telling cabinet members to re-examine all options.
The council is committed to 'harmonising' services inherited from the three former district and borough authorities and Northamptonshire County Council during last year's local government restructuring.
But one south Northamptonshire councillor, Ian McCord, said there was no financial reason for the charge.
The Deanshanger Independent said: "If Cabinet insist and make this charge they are doing so because they want to stiff the residents for £42 quid a year just because they can.
"There is no financial reason. No new services will be provided.
"The cost of living is rising. Fuel, heating, gas, electricity costs are rising as well as general increase in council tax. It is time to give the residents a break."
"There is £170m in the bank this additional money is not needed. There is no need to do what you do in Northampton."