Employers paid £1.7 billion more in bonuses this April than last year as they took advantage of the new 45p top tax rate.
Many businesses held over pay-outs normally made in March, when they would have had to pay 50p in the pound to the Treasury.
Bonuses in the finance and insurance industry were more than double in April than they were the year before, despite an outcry earlier this year that forced banking giant Goldman Sachs to back down on plans to defer bonus payments to UK staff.
TUC general secretary Frances O'Grady blamed Chancellor George Osborne for giving a "gift worth tens of millions of pounds, courtesy of the taxpayer" to the super-rich by giving them plenty of notice to defer the pay-outs.
A report from the Office for National Statistics said the usual definition of "bonus season" from December to March did not apply, with April seeing "unusually high levels of bonus payments".
Total bonuses for the tax year from April 2012 to March 2013 were up 1% to £36.9 billion, giving an average of around £1,400 per employee which was unchanged from last year, the ONS figures showed.
But there was a much higher rise when taking into account the shift in many bonus payments to the new tax year.
Bonuses from May 2012 to April 2013 were £38.6 billion, an increase of 4%, with the average bonus per employee at £1,500 over this period. Of this, £14 billion was paid in the finance and insurance industry, also a 4% increase.
The ONS report said: "The increase in bonus payments in April 2013 partly reflects the deferrals of bonus payments by some businesses which reported that they had chosen to pay the bonuses usually paid in March in April this year."
Total bonus payments in March were lower, down from £4.9 billion to £4.2 billion.
In the finance and insurance industry, pay-outs were slightly higher in March, from £3.5 billion to £3.7 billion.
But the figure in April soared from £600 million last year to £1.3 billion this year. In the rest of the economy they went up from £1.9 billion to £2.9 billion.
The best average bonus per employee for 2012/13 was in the finance and insurance industry at £11,900. This was a £100 decline compared to the previous 12-month period - without taking into account the spike in April this year.
Lowest pay-outs were in the education, and health and social work industries, where bonuses per head were negligible.
On average, private sector employees received £1,700 in bonuses for the period, 17 times higher than the average public sector worker's bonus of £100 - when excluding the part-nationalised banks which took the figure to £300.
However, private sector workers on average receive less in regular pay than people working in the public sector, the ONS said.
Figures earlier this month showed the bumper round of April bonuses was so significant that it caused a spike in national average earnings for the three months to June.
The disclosure that employers apparently shifted large pay-outs to take advantage of tax changes is likely to add to public anger over executive pay culture, especially in a financial sector that had to be bailed out by the taxpayer.
Ms O'Grady said: "The return of big bonuses shows Britain is booming for the super-rich.
"While ordinary people suffer the longest wage squeeze in over a century, those at the top have seen bonuses rise by a stonking 4%.
"Not content with giving the super-rich a tax cut, the Chancellor has also showered them with an extra gift worth tens of millions of pounds, courtesy of the taxpayer, by giving them plenty of notice to defer their bonuses and avoid the 50p tax rate."
Earlier this year Goldman Sachs was forced to back down on plans to defer bonus payments to UK staff after then Bank of England governor Lord King attacked the move.
He told MPs: "I find it a bit depressing that people who earn so much seem to think that it is even more exciting to adjust the timing of it to get the benefit of a lower tax rate - which they will benefit from in the long run to a very great extent - knowing that this must have an impact on the rest of society, when even now it is the rest of society which is suffering most from the consequences of the financial crisis."
Chris Leslie, shadow financial secretary, said: " While ordinary families on low and middle incomes are seeing their living standards fall, those at the top are reaping the benefits of David Cameron's tax cut for millionaires.
"Bonuses soared in April as bankers delayed their pay-outs to take advantage of the 50p tax cut. Millions of pounds of revenue will have been lost as a result, at a time when people across the UK are facing a cost of living crisis."