Young graduates in England need a postgraduate degree to get significantly ahead in earnings, official income data suggests.
Graduate earnings figures show that up to the age of 30, postgraduates typically earn £9,000, or about 40%, more than those without degrees.
This is double the £4,500 per year gap - about 21% - between those with an undergraduate degree and non-graduates.
Universities Minister Chris Skidmore welcomed the "graduate premium" in pay.
The graduate earnings figures for 2018, published by the Department for Education, show that for graduates aged between 21 and 30, the typical salary is £25,500, compared with £21,000 for non-graduates.
But with more students than ever getting undergraduate degrees, the biggest earnings premium is now for those who stay on for further studies, with postgraduates typically earning £30,000.
This gap applies across the whole working population, between the ages of 16 and 64, with postgraduates averaging £40,000, compared with £34,000 for graduates and £24,000 for non-graduates.
The government has commissioned a review of whether undergraduate fees of £9,250 per year in England represent value for money.
These latest official figures show a narrowing advantage for young graduates - the annual pay gap closing from £6,000 between graduates and non-graduates in 2008 to £4,500 and a lower proportion of young graduates in "high skilled" jobs in 2018.
The earnings figures show that pay levels for all levels of education have faced a decade of stagnation and real-terms decline.
In 2008, the typical young graduate was earning £24,000 - and by 2018, if it had simply kept pace with inflation, that would have risen to about £31,500.
But the typical young graduate in 2018 was only earning £25,500, representing a significant drop in real-terms earnings.
Below these national figures for young graduates there are very wide differences - depending on gender, ethnicity and regional jobs markets.
- Female graduate earnings average, up to the age of 30, average £24,500, but male graduates average £28,000
- White young graduates average £26,000, while black graduates average £22,000
- Graduates with first-class degrees earn £27,000, while those with a 2:2 degree earn £24,000
- In London, young graduates average £30,000, while in the north-east they average £21,000
Mr Skidmore said: "There is clearly much further to go to improve the race and gender pay gap.
"We have introduced a range of reforms in higher education which have a relentless focus on levelling the playing field, so that everyone with the talent and potential can not only go to university, but flourishes there and has the best possible chance of a successful career."