Scottish taxpayers and businesses face a “Scotland surcharge” of up to £1 billion over the next four years, the Scottish Conservatives have claimed.
The party said the SNP’s plans for income tax, business rates and its stamp duty replacement - land and buildings transaction tax (LBTT) - will make Scotland the “highest-taxed” part of the UK.
The Scottish Government said the measures would make taxation “fairer and more proportionate” while also raising extra cash.
The Tories have published their own analysis of SNP policies as new revenue-raising powers come to Holyrood.
Scottish leader Ruth Davidson said the plans will “clobber hard-working families”.
The analysis comes ahead of a Tory conference debate to “celebrate the union”.
The party has looked at the Scottish Government’s pledge to freeze the higher income tax rate threshold in contrast with the UK Government’s plan to raise it over the next four years.
The policy will boost Scotland’s budget by about £370 million a year by 2020/21 through block grant adjustments and extra tax revenue, it states.
The Tories have also examined the impact on Scotland’s finances of the Government’s decision to double the large business supplement from 1.3p to 2.6p - a move which could generate around £65 million each year, it claims.
Meanwhile, the party estimates that LBTT will generate up to £27 million more than stamp duty by 2020/21.
Ms Davidson said: “It’s clear the SNP want to clobber hard-working families and make Scotland the highest-taxed part of the UK.
“Just as we should be telling the world we’re open for business and investment, the First Minister wants to drop a billion-pound bombshell on the Scottish economy.”
Scottish Secretary David Mundell said: “The Scotland Act 2016 devolves unprecedented powers over tax and welfare to the Scottish Parliament.
“How the SNP use those powers is now up to them - and they will have to account to the Scottish people for their plan to tax Scotland £1 billion more than England over the next four years.”
A spokesman for Scotland’s Finance Secretary Derek Mackay said the Scottish Government was protecting public services while the Tories cut them.
Ms Davidson wants to “slap additional taxes on ill health and education by bringing back prescription charges and tuition fees”, he added.
“We are making taxation fairer and more proportionate to the ability to pay, while also raising additional revenue.
“Our income tax proposals for 2017/18 and beyond will protect lower-income taxpayers - but also generate extra revenue of around £1.2 billion by 2021/22 to invest in key public services like the NHS while mitigating the impact of Tory austerity.
“At the same time, we are helping companies to grow the economy through measures including our small business bonus scheme - it already offers greater support than the equivalent in England and has already saved Scottish firms more than £1 billion, but we are expanding the scheme from next year so that it lifts 100,000 properties out of rates altogether.”
Scottish Liberal Democrats Willie Rennie said the Tories’ analysis was an attempt to divert attention “from the chaos they have unleashed with Brexit”.
On the Tory conference debate, he added: “Rather than celebrating, the Tories should be apologising for putting the future of the United Kingdom at risk.
“Their recklessness on the EU opened the door for the SNP to talk up a second independence referendum. Ruth Davidson’s party cannot be trusted on the union or on Europe.”
Labour leader Kezia Dugdale said: “The Tories’ complete and utter failure to work out a plan for Brexit gave Nicola Sturgeon fresh ammo in her quest to break up the union.
“So don’t let Ruth Davidson, Theresa May, or any other Tory ever tell you that the union is safe in Tory hands. It is not.”