The former Wexford primary school teacher has sold more than 25m books translated into 44 languages around the globe about the adventures of his teenage criminal mastermind, Artemis Fowl.
Now, accounts filed by Colfer’s firm, Artemis Fowl Ltd, show that the firm’s accumulated profits last year jumped by just under €800,000 going from €1.825m to €2.622m.
The cash pile at the firm during the year also rose sharply, going from €1.843m to €2.6m.
In July 2013, Disney added to Colfer’s coffers when they confirmed that the adventures of Artemis Fowl are to be made into a movie with one of Hollywood’s best- known actors, Robert de Niro, acting an executive producer on the project.
One of the most influential figures in modern cinema, Harvey Weinstein, is to produce. The film will cover the first two books of the series.
Development in the movie stretches all the way back to the early 2000s, but it moved forward significantly only this month with the producers reportedly securing Belfast native Kenneth Branagh to direct.
Branagh’s reputation in children’s movies is currently riding high after his hugely successful Disney’s Cinderella raked in $542m earlier this year.
Colfer — who celebrated his 50th birthday in May of this year — published the eighth and final book in the best-selling Artemis Fowl series in 2012.
However, his finances have continued to flourish since with accumulated profits at his firm increasing more than three fold from €713,201 in 2012 to €2.6m to last year.
The the firm made a fresh investment of €201,918 in an unidentified financial asset last year.
The 2014 accounts confirm the firm’s revenues are generated through amounts received for book advances and royalties during the year.
The accounts show that, at the end of last year, the firm owed €94,555 in corporation tax, with the amount owed in PAYE/PRSI totalling €57,200.
Colfer resigned from his teaching post after the success of the debut Artemis Fowl novel in 2001.
The documents show that Colfer’s wife, Jackie Colfer, also acts as a director of Artemis Fowl Ltd.
The initial print run for the final Artemis book, The Last Guardian, ran to 1m copies and it won Children’s Book of the Year at the 2012 Bord Gais Energy Irish Book Awards in the senior category.
The first seven books featured Artemis Fowl as an anti-hero and with the eighth book culminating in Artemis Fowl being a hero who is prepared to sacrifice everything for a good cause.
In June of this year, Colfer published the third of his books from the Witness Anonymous Relocation Programme series with the release of The Forever Man to very enthusiastic reviews.
On his website, Colfer says: “I will keep writing until people stop reading or I run out of ideas.”