The proposal was first announced by the then Finance Secretary Shona Robison in her budget in January.
But at the time the government did not know how much the tax would raise as the measure was not included in the financial modelling.
According to the consultation paper, the new bands are estimated to raise between £12m and £16m a year in total across Scotland, less than half of 1% of total Council Tax income.
Band I will apply to homes worth between £1m and £2m, and Band J to those worth more than £2m, based on current values rather than the 1991 reference point used for the existing eight bands.
The relatively modest sums involved reflect the small number of properties likely to be affected.
The Government’s own estimates suggest as few as 760 homes could fall into Band J, the top band, and as few as 12,680 into Band I.
That is fewer than 1% of all homes in Scotland.
Making the case for the change, the paper argues that under the current system, properties “worth several million pounds can face a Council Tax bill that is only marginally higher than a property worth a fraction of that amount”.
They give the example where a multi-million-pound home in Band H could face a Council Tax bill less than £1,000 more than a property worth one tenth of its value in Band G.
These properties have a tax rate of 2.45 relative to Band D
Under the illustrative rates published alongside the consultation, Band I properties would face a multiplier of 2.886 relative to Band D, equivalent to about £4,770 a year, while Band J properties would face a multiplier of 4.628, equivalent to about £7,650 a year.
That amounts to Band I households paying around £720 more than the current Band H average, and Band J households paying around £3,600 more.
To identify which properties fall within Band I or Band J, Scottish Assessors will carry out a “targeted revaluation” of properties estimated to be worth more than £1m at 1 April 2026 values.
High-value properties are also unevenly distributed across Scotland, concentrated in and around the cities and in some rural areas, meaning the additional revenue will be worth more to some councils than others.
The split between local authorities is still to be agreed with Cosla.
The consultation is seeking views on whether the illustrative multipliers should be set higher, lower, or left unchanged, with final rates to be set through primary legislation.
Deputy First Minister and Cabinet Secretary for Finance Jenny Gilruth said the SNP government’s approach to tax was “based on fairness”.
“As it stands, some multi-million pound properties have council tax bills that are not materially different from those faced by people living in far more modest homes.
“Our progressive approach to taxation helps to target investment in economic growth, deliver public services and support cost of living measures not available elsewhere in the UK, such as free tuition, free prescriptions and our plans for a £2 bus fare cap across Scotland.
“Additional revenue raised through these new council tax bands will be retained in full by local government to support the local services communities rely on – unlike the UK Government‘s proposals for a similar scheme that are set to be returned to the Treasury.
“In launching this public consultation, we are keen to hear the views of people and communities right across Scotland.”
Scottish Conservative finance spokesman Craig Hoy described the proposal as “performative” and “another example of a headline-grabbing SNP idea that falls down on closer inspection”.
He added: “In targeting a small minority of properties, the revenues these new bands would bring in won’t touch the sides, and that’s before the administrative costs are factored in.
“But there is a real danger that these punitive rates put people off buying in Scotland, which could damage the entire housing market.
“A mansion tax would also unfairly hit some asset-rich, cash-poor individuals – such as widows on modest pensions who are still living in the family home.
“Like rent controls, a mansion tax sounds superficially attractive but would actually do lasting harm to the housing market.”
However, the Scottish Greens welcomed the consultation, describing it as an “important milestone”.
Lorna Slater said: “The mansion tax will raise vital funds for schools, libraries and other local services, while helping to respond to Scotland’s housing emergency.
“It is happening because Scottish Green MSPs and housing campaigners made it a priority in budget negotiations.
“Alongside the private jet tax, which was also secured by the Greens, it reflects a simple principle. If we want properly funded public services, we need to ensure that those with the greatest wealth are paying their fair share.”
