Autism Concern has been running for 17 years and has supported thousands of people in the county. The charity faces the funding shortfall because of a major drop in grants and donations.
The credit crunch and general economic downturn are among f
actors to blame.
Now a major fundraising appeal is being launched to save the charity and give it the opportunity to find new long-term funding sources.
Director Sylvia Tilaks said: "This is the most desperate situation. Our reserves and income are so low that if the money isn't found, we will have to close for good at Christmas.
"Providing such a wide range of invaluable services to so many local people is very expensive. We are a lean charity with running costs at a bare minimum, but are still struggling to meet demand for services.
"Legally we cannot continue to operate unless this money is found. That is why we have launched the biggest appeal in the charity's history. It will help us find ways to secure the long-term future of Autism Concern."
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