The County Councils Network (CCN) has said scrapping 213 smaller councils in England to replace them with 25 local authorities would save £3 billion.
A report put together for CCN by PricewaterhouseCoopers (PwC) said merging district and county councils in each area into a single unitary council could save £2.94bn over five years nationally.
However, the report also warns that creating two unitary authorities in one county would reduce the savings by two thirds.
It has been suggested in some two-tier areas that through the process of reorganisation, disaggregated smaller unitary authorities could delegate strategic growth functions, such as transport, to a new combined authority to maintain strategic scale in delivery.
Across most of England, local government operates under a two-tier system, with both a county council and a district council providing services.
The report concludes a single unitary in each area would reduce complexity and give communities a single unified voice to Government.
CCN says that the report outlines a ‘compelling’ financial case for the creation of more single county unitaries in areas where councils seek reorganisation.
It said this will help ‘safeguard’ council services in the wake of the pandemic, while ensuring councils are of the necessary size to drive forward the economic recovery and devolution agendas.
PwC summarise that the “implementation of single unitaries in each of England’s 25 two-tier areas would deliver significantly greater benefit” and if “an alternative approach be pursued the process of disaggregating current county services does present a number of material costs, but also non-financial risks and complexities”.
Cllr David Williams, chairman of the County Councils Network, said: “The consequences of coronavirus for local government finances, and the need to work quickly to support the economic recovery, means more councils want to look again at how local government is structured in their area.
“This Government has already signalled that it wants to see many more unitary councils created and it is important we get it right for our residents – we do not want to look back on this period as a missed opportunity.
“The findings from PwC show there is a compelling financial case for the creation of more unitary counties where councils seek reorganisation.
"They will provide significant savings to support frontline services and the stability needed to safeguard care services as we continue to mitigate the impact of coronavirus.
"Crucially, it will create councils of the necessary size to support local economies to recover from the pandemic and drive forward the devolution and levelling up agendas."
The Government is expected to publish its own proposals on overhauling local government in the autumn.