The result of the Scottish election may almost be a foregone conclusion, but that doesn't stop the contest for Holyrood being the most important since devolution.

While the polls show the SNP on track to win its third term in power, securing an unprecedented second majority government, the devolution of new tax powers has given the fifth ever Scottish Parliament election a new twist.

From April 2017, MSPs will take charge of income tax rates and bands, one of the key measures in the new Scotland Act that was introduced following the 2014 independence referendum.

Holyrood will be responsible for raising part of its own income for the first time, with plans over how to do this dividing the parties.

SNP leader Nicola Sturgeon has already ruled out raising the basic rate of income tax for the five years of the next parliament, and has rejected plans for a 50p top rate of tax for those on £150,000 a year or more for the first year at least.

In contrast, both Scottish Labour and the Scottish Liberal Democrats want to put 1p on the basic rate of income tax, and would use the cash raised to invest in local services, with the Lib Dems to put all the funding into education.

Labour also plans to raise additional cash for schools by increasing the top rate of income tax from 45p to 50p.

The Scottish Greens would raise the top rate further still, to 60p for earners on £150,000 a year or more, as part of a range of reforms that the party claims would leave those making up to £26,500 a year better off.

The Conservatives, however, have pledged not to make Scotland the highest taxed part of the UK, with Ruth Davidson's party instead wanting to cut the levy in the "medium term".

So the results of the May 5 election will impact on at least some of Scotland's voters in the pocket.

There could also be significant effects on the parties at Holyrood, depending on the outcome of the vote.

The Tories are seeking to capitalise on Labour's falling levels of support and overtake Kezia Dugdale's party to become the official opposition - a result which would send out political shock waves.

Labour, which was for so long the dominant party north of the border, lost all but one of its Scottish seats at Westminster last year, with the party now admitting it needs to put greater focus on winning seats via Holyrood's regional lists.

At the party's recent Scottish conference, general secretary Brian Roy told activists this election would ''not be a traditional key seat campaign''.

He added the party had "learned the mistake of the past when we did not place enough importance on the regional list votes and did not organise effectively on that basis".

After the SNP won all but three of the 59 Scottish seats at Westminster in the 2015 general election, it will be targeting seats the length and breadth of Scotland, while there has been speculation that Labour could fail to win any of the 73 constituency seats.

The Scottish Greens are hoping to capitalise on a surge in membership which has seen the party swell its ranks from about 1,000 in 2011 to more than 9,000.

The party's best Holyrood performance was in 2003 when seven Greens were elected, and co-convener Patrick Harvie is hopeful 2016 will see a record number of Greens in the Scottish Parliament.

The UK Independence Party will also be looking to capitalise on its success in the 2014 European election, when David Coburn was voted in as one of Scotland's six MEPs, becoming Ukip's first elected representative north of the border.

Some polls have suggested Nigel Farage's party could win a seat at Holyrood, and the upcoming EU referendum could help the party, which supports a vote to Leave, increase its vote.