David Cameron has defended his government's "bold" decision to cut tax for Britain's highest earners.
The prime minister spoke out after Chancellor George Osborne announced in Wednesday's Budget that he would slash 5p off the 50p tax rate.
Labour have criticised the move, branding it unfair, but Cameron today accused them of political point scoring.
He hailed Osborne's "really big, bold decision to cut the top rate of tax" as he addressed the Scottish Conservative conference in Troon, Ayrshire.
The prime minister said: "It's simple - if you want to have a dynamic, enterprise economy, if you want to attract the very brightest and best here, then you cannot have the highest rate of tax in Europe."
Shadow chancellor Ed Balls complained yesterday that Osborne had "decided his priority to make our economy stronger is to have one tax cut - a huge tax cut - for people above £150,000".
He told BBC Radio 4: "People will say 'How can that be the priority, how can that be fair, how can that be right?' Isn't this just the same old Conservative Party playing its games?"
But Cameron said today that the tax cut could encourage business and investment in Britain.
He said: "This is about sending a message out to the world that if you want to invest, create, invent, locate, make money, make jobs, then come and do it right here."
He said he wanted to "tell the truth about the 50p top rate of tax", as he turned on Labour.
The prime minister said Labour, who had been in government for 13 years, had only brought in the 50p tax rate "one month before the election they knew they were going to lose".
He insisted Labour's attack "wasn't about fairness", adding: "It was about making a political point, plain and simple." Cameron said the measure in the Budget he was most proud of was the increase in personal tax allowances, which he said meant his Government was "taking almost two million people out of tax altogether", including 73,000 people "right here in Scotland".
He also used his conference address to defend controversial welfare reforms, which will see a cap brought in on the amount of benefits a household can receive.
The Tories, he said, were the only party with "the courage" to tackle the issue.
The prime minister said: "We said it wasn't right that people could take home more in benefits than the average working family earns.
"We proposed a cap of £26,000 on what one family could have in benefits."
He described this as "one important antidote to all those years of failure, the wasted lives, the families where no-one's ever worked, the epidemic of irresponsibility that has taken root in so many of our communities".
And he hit out at Labour and the SNP for failing to support the measure.
"If you want to keep the welfare system as the woeful, pitiful, factor of hopelessness it is today, if you want to back away from the big decisions we need to fix our society, then vote Labour or SNP," the PM said.
"Because believe me, it's only this party that will ever have the guts to change anything and get on top of our welfare culture and change it for the good of people in our country."