Bjorn Ulvaeus of Abba has been accused of avoiding taxes of 16m kronor (£1.2m) by authorities in Sweden.
Bjorn Ulvaeus wrote Abba's hits with fellow musician Benny Andersson
The musician was "paying less tax" than he should have done on royalties from the group's hits, according to Swedish Tax Authority official Victor Palm.
And some income may have been channeled through overseas companies, he added.
Last year Ulvaeus - whose financial advisor was not available for comment - was told to pay 65m kronor (£4.8m) of tax, a ruling he is appealing against.
In that case, dating back to April 2006, the Swedish government initially demanded 87m kronor (£6.5m) from the star.
These were from back taxes related to contracts which he signed before moving to Britain in 1984.
The government later agreed to reduce its claim, but it is not known when a court will consider the appeal.
Abba have sold 370 million records and Ulvaeus also co-wrote the musical Mamma Mia.
With Benny Andersson, Ulvaeus was responsible for hits such as Waterloo and Dancing Queen, as well as the stage show Chess.
But Ulvaeus said last year that the group would never stage a reunion as their "creativity" together had now disappeared.