In fewer than three weeks, decision time will be upon us and the Holyrood elections will be here.

In the past week the parties have begun to publish their manifestos, giving further detail of how they would want to run the Scottish Parliament.

It started loudly and with gusto as David Coburn and Nigel Farage from UKIP were played into their press conference to 'Scotland the Brave' on the accordion. Their pledges include a new 30p income tax rate along with cutting "town hall fat cat salaries".

Next up the Scottish Greens who want to introduce a 60p rate for income tax for those earning over £150,000 and a new 43p rate for those who make over £43,000. Elsewhere they pledged to create 200,000 jobs in oil and gas decommissioning, renewables and housing.

The Scottish Conservatives said they would build 100,000 new homes across Scotland over the next five years, including a £1bn pledge to improve energy efficiency. They also underlined their commitment to ensure taxes in Scotland are not higher than any other part of the UK.

Finally, the Liberal Democrats want to increase tax by a penny to pay, in part, for a "pupil premium" that they say would raise standards and close the attainment gap. They have also pledged to transform the way mental health issues are dealt with in Scotland while recruiting more GPs.

Noticing a trend here? Yes, tax, tax and more tax. It's without doubt the biggest issue in the election campaign with each party having a different stance. Labour and the SNP have already set out their position before their manifesto launch - Kezia Dugdale wants to increase income tax by a penny and raise the rate for top earners to 50p while the SNP have pledged to freeze tax rates but have ruled out introducing that 50p rate for those earning over £150,000. They also promised to raise the personal allowance to £12,750 by 2020/21 by setting a zero rate.

This week the left-leaning think tank the IPPR released its analysis of how much extra money could be raised from each of the party's policies on tax. It ranges from zero under the Conservatives to £300m with the SNP, £750m under the Liberal Democrats, £950m from the Greens and £1.2bn with Labour.

It means voters now have a clear choice. Should taxes increase to raise additional capital? Would you want to pay more to give the Scottish Government extra cash? Something to mull over before May 5th.

And what else have we learnt from the manifesto launches? Perhaps most significant was Ruth Davidson's admission her party will not form the next government. She said her chances of becoming the next First Minister were "next to nil" and made it clear her focus was on becoming the opposition at Holyrood.

For some this was a surprising statement for a political leader to make but Ruth Davidson knows the fight for second place is close. A YouGov poll this week found more voters think she would make a better leader of the opposition than Kezia Dugdale. Similarly, 32% said she was the more competent of the two, compared with 12% for Ms Dugdale.

Hence why the Conservative manifesto launch was so heavily branded with Ruth Davidson's name; it appeared on the lecture, the backdrop and was even projected onto the walls. The party know how popular she is and they are determined to capitalise on it.

But the Labour leader is taking a gamble of her own. While the SNP will launch their manifesto next week, Labour have said their launch will be not be until eight days before the polls open. Nicola Sturgeon said it was "shambles" but the Labour hit back saying it meant the SNP couldn't copy their ideas.

Either way thousands of postal votes may well have been cast by then time Labour's manifesto is launched. Kezia Dugdale hopes waiting until the end of the campaign will mean her party's pledges are upmost in voters' minds.

Carole Erskine is STV's political reporter and can be contacted carole.erskine@stv.tv