SCOTS will be asked how much income tax they should pay as part of a Holyrood inquiry into new powers coming into force next year.

Finance Secretary John Swinney will set the first ever Scottish Rate of Income Tax (SRIT) in September, when he announces his budget for the 2016/17 financial year.

Holyrood's finance committee is launching an inquiry today into how the power should be used and whether taxpayers and employers are prepared for the change.

The consultation, which members of the public are urged to take part in, asks how much income tax Scots should pay and why.

It also seeks views on how extra revenues should be spent if income tax is raised, and what services should be cut if it is reduced.

A report based on people's responses will go to parliament days before Mr Swinney makes arguably the biggest decision in his eight years as Finance Secretary.

His call could also have a bearing on the Holyrood election, which takes place a month after people start paying the new Scottish income tax next year.

At present, income tax is levied in three bands.

Those earning between the tax-free personal allowance of £10,600 and £31,785 pay the basic rate of 20p in the £1.

Earnings between £31,786 and £150,000 attract a higher rate of 40p, and earnings over £150,000 are taxed at the additional rate of 45p.

From April 1 next year, those rates will be reduced by 10p in Scotland and the Scottish Government will set its own rate, which could be higher, lower or the same.

It will keep the revenue and Holyrood's annual block grant from the Treasury will be cut to reflect its reduced revenues from Scottish taxpayers.

If the SRIT is set at a like-for-like 10p in the pound, it will raise approximately £5.3 billion, a sizeable chunk of the Scottish Government's £30bn overall budget.

Because the SRIT applies to all three bands across the board, any changes will have a proportionately bigger effect on basic rate taxpayers.

The system has been criticised because it does not allow the Scottish Government flexibility to set different rates in different bands.

Finance committee convener Kenneth Gibson said: "From next year, revenue from the Scottish rate of income tax will be a significant part of the money spent on Scotland's public services.

"There are key decisions to be made on the level the Scottish rate should be set at and how taxpayers and employers are informed about the introduction of SRIT."

He added: "It is important for the finance committee to scrutinise the introduction of this new power and I would encourage people to submit their views to inform the committee's inquiry."

To help people, the Scottish Parliament has created an interactive online 'SRIT Calculator'.

It allows taxpayers to enter their salary and discover how much of their total tax goes direct to the Scottish Government and how much to the UK Treasury at different levels of SRIT.

The calculator, on the parliament's website, also enables the envious or angry see what happens to a Scottish Premier League footballer's pay or an MSP's salary in terms of tax.

The SRIT was a key part of the 2012 Scotland Act, which drew on the Calman Commission on further devolution.

The Act also devolved two other taxes, the new Land and Buildings Transaction Tax which replaced Stamp Duty, and Landfill Tax. They became the first taxes to be levied by a Scottish parliament in 300 years when they came into force in April this year.

The SRIT will be superceded in a few years' time under proposals in the Scotland Bill, which was unveiled this week.

It will transfer almost full control over income tax to the Scottish Parliament.