The Pension Schemes Act 2015 has become law after receiving royal assent yesterday.
According to pensions minister Steve Webb, the passing of the Act "marks the culmination of a five-year pensions revolution under this coalition government".
The Act brings the new pension freedoms into force on 6 April 2015 and other "successes since 2010" including auto-enrolment, the pension charge cap, "defined ambition" risk-sharing schemes and "triple lock" protection, which guarantees the rate of basic state pension rises in line with earnings, prices or 2.5% - whichever is higher.
The Act also introduces legislation on the government's retirement guidance service Pension Wise for people claiming to pretend to offer official Pension Wise guidance.
Webb said: "There is a real appetite from employers to offer high-quality pensions for their staff and the new defined ambition pensions made possible by this Act will enable a new generation of better, fairer schemes.
"The Act also protects the new pension freedoms and flexibilities, so people have control of their pension pots, and know it is a criminal offence for scammers to pretend to offer official Pension Wise guidance."
Economic secretary to the treasury Andrea Leadsom said: "Today a new criminal offence comes into effect which means that people passing themselves off as providing the official Pension Wise service will face a fine or prison. This will help ensure Pension Wise is a brand and service that people trust and to protect people from potential scammers."
The National Association of Pension Funds (NAPF) welcomed the Act, but said with schemes working "flat out" to implement the reforms in time, the government should speed up to provide "the missing pieces of the puzzle".
Joanne Segars, chief executive at NAPF, said the government needed to ensure all communications to savers were realistic, so savers could "make solid plans for retirement and avoid disappointment".
"To help savers the NAPF has outlined three top tips for taking advantage of the new pension freedoms. These are - be informed, be realistic and take your time," said Segars. "The NAPF is committed to making these reforms work, but ultimately we must not forget it's about savers not voters. They are not a silver bullet to secure the silver ballot."