The “skills wallet” scheme will give people £4,000 aged 25, £3,000 aged 40 and £3,000 aged 55, the party has revealed.
The money can only be used for approved education and training courses, and will be paid for by reversing cuts to corporation tax to bring the rate back to 20 per cent, according to the Lib Dems.
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The pledge builds on the Lib Dems' party conference promise to give every adult over 25 £9,000 for lifelong learning, dubbed a “Personal Education and Skills Account” at the time.
Adult education promise
Liberal Democrat business spokesman Sam Gyimah said the Lib Dems would, if elected, usher in a new era of learning throughout adult life.
He said: "In an ever-changing workplace, people often need to develop new skills, but the cost of courses and qualifications shuts too many people out.
"By stopping Brexit and investing in our skills wallets, Liberal Democrats will empower people to develop new skills so that they can thrive in the technologies and industries that are key to the UK's economic future and prosperity."
As education is devolved, the policy applies to England only. But the party said that extra funding would be available under the Barnett formula for Scotland, Wales and Northern Ireland.
In response, a spokesman for the Conservative Party said: "Corporation tax receipts are at an all-time high thanks to the Conservatives' management of the economy since Labour's great recession.
"Hiking taxes on businesses will hit economic growth, meaning fewer jobs and less money to invest in public services like schools and hospitals."