The National Trust is putting up membership fees to fund the rising costs of looking after historic houses, coastline and countryside in its care, it said.
A rise of 50p a month on average for members, who now exceed five million, will help fund its biggest ever programme of conservation repairs, maintenance and improvements, the charity said.
Costs of looking after the 300 National Trust historic properties, 778 miles of coastline and more than 600,000 acres of land rose by 15% last year, as the charity spent the equivalent of £2 million a week on conservation work.
Over the last two years, the Trust has spent a quarter of a billion pounds on looking after historic homes, landscapes and gardens in England, Wales and Northern Ireland, it said.
Major programmes include work such as restoring the roof of The Vyne, Hampshire, and the famous gardens at Stowe in Buckinghamshire.
Conservation work this year includes projects such as the "re-dedication" of Scafell Pike and 12 other Lake District peaks as a memorial to those who died in the First World War.
To fund the Trust's work, members over the age of 26 will pay £4.20 a year more, as individual membership rises to £69, while family membership goes up £5.40 to £120 a year from March 1.
The Trust is writing to around a million over 60s to tell them it will continue to reward loyal membership with a 25% discount, with loyal senior fees up from £48.60 to £51.48, or from £80.40 to £85.20 for joint membership.
And the organisation will introduce a new £10 junior pass for five to 17-year-olds in response to children increasingly being looked after by grandparents and other family members while parents are at work.
Sharon Pickford, membership director, said: "We are a charity, we don't receive any direct Government funding and our conservation costs are increasing.
"We need help from our members to look after these amazing places.
"Last year, we spent the equivalent of more than £2 million a week on conservation work.
"This included helping to fund big projects such as finishing the 30-year restoration and conservation of Kedleston Hall in Derbyshire, the continuing restoration of Knole in Kent and repairing the roof at the Vyne in Hampshire; plus restoring the famous gardens at Stowe in Buckinghamshire and Standen in West Sussex."
She added: "But it's not just the big projects we need to fund; money raised through membership also helps fund improvements to facilities - such as car parks, cafes and delivering a programme of events for visitors.
"Over the last few years we've also responded to members' feedback to open our doors for longer and for more places to open for 363 days a year.
"We couldn't do all of this without the vital support of our members and we thank them for their continued support."