The news is set to prove a huge blow for householders already struggling under the weight of bills and follows increases of between 7-25% at the start of this month for adult premiums on a range of its plans.
The insurer says the latest rise is a direct result of the recent health insurance levy increase by the Government.
Quinn has over 458,000 subscribers.
The 6% increase will not apply to its Essential First scheme, which is its lowest cost entry plan.
Quinn Healthcare Managing Director Donal Clancy said the dramatic changes to the health levy had not been anticipated.
Quinn Healthcare said that the recent health levy increase of 40% and other changes to age related tax relief on health insurance will cost it €20 million this year.