Legislation to create single police and fire services is expected to clear its final hurdle in Holyrood.
The Police and Fire Reform Bill would see Scotland's eight regional police and fire services merge into respective single units by April.
Justice Secretary Kenny MacAskill has said the unification is largely cost-driven but pledges to make "a virtue out of a necessity".
The Bill is designed to create estimated "efficiency savings" of £1.7 billion over 15 years, largely through reducing duplication of senior officer roles and back-office staff.
Questions remain over whether the services are liable for a £30 million tax bill.
The Treasury has yet to formally notify the Scottish Government whether they will waive a VAT bill incurred through centralisation. The Scottish Government has said it understands that the answer will be no and has accounted for VAT in its financial projections.
Meanwhile, opposition parties and police bodies fear that the cost-saving reforms will not deliver the projected savings and could see a mass cull of police civilian staff. Labour has devised a worst-case scenario that could see the loss of 3,200 jobs.
Spending watchdog Audit Scotland has advised the Scottish Government to learn from previous cost-saving efforts that fell short of expectations and monitor police and fire budgets closely.
A recent Audit Scotland sample suggested previous public sector mergers could have created just a fifth of their projected savings, with additional costs hidden by poor accounting.
The Unison trade union has criticised the centralisation of police services from the start, raising concerns about a "lack of local democratic accountability", the VAT bill and the de-civilianisation of the force.