A council told it should be scrapped due to financial failings paid almost £1m to a consultancy firm owned by its former chief executive, figures obtained by a union show.
Damon Lawrenson took over at Northamptonshire County Council in 2017 but left by "mutual consent" this week.
The GMB said knowing he was paid the money for prior consultancy work would be a "kick in the teeth" for staff.
Salaries reflect responsibilities, the council said.
Mr Lawrenson took over as interim chief executive in October and had been contracted to stay until June 2018 before agreeing to leave the role.
In all, Freedom of Information requests show he was paid £931,364 for consultancy work over five financial years from 2008-11 and 2016-18.
A council spokesman added £560,000 paid to Mr Lawrenson's company, DDL Consultancy, related to work done between 2008 and 2011.
GMB union organiser, Rachelle Wilkins, said to spend almost £1m on consultancy "while people are losing their jobs and services are being cut is particularly sickening".
"Conditions for the workforce have deteriorated," she added. "Meanwhile fat cats like Damon Lawrenson have got richer."
The council spokesman said Mr Lawrenson had not been eligible for sick pay, holiday pay or pension contributions.
"Salaries reflect responsibilities associated with the posts, many of which require highly-qualified, professional staff, while being mindful of the necessity of providing value for money," he said.
Earlier this month, the BBC revealed Mr Lawrenson was being paid £1,150 per day in his role as interim chief executive, with Unison branch secretary for the county council, Penny Smith, saying his appointment had "lacked transparency".
Prior to that he had worked as interim finance director between July 2016 to October last year.
Last week, a government report said the county council should be scrapped and replaced by two new unitary authorities by 2020.
Secretary of State for local government Sajid Javid had ordered the inspection in January.