Camilla, who already has financial advisers, is applying to join the London Mutual Credit Union in Peckham where she will have access to its financial services which aim to teach members how to save around £20 to £40 each week.
She will also be eligible for payday loans normally used by people in "crisis" situations which have 28.6%APR interest rates, compared with other lenders who can charge up to 4000% APR.
On her first visit to the Peckham branch, she praised its services and said: "I think everybody needs that bit of help to show them how it's done. That personal touch just makes a difference."
The non-profit organisation is one of London's largest and provides services to anyone who live or works in the Southwark, Lambeth, Westminster and Camden boroughs. It runs by lending out its members' savings and encourages customers to take control of their money and only borrow amounts they can afford to repay.
LMCU will be the first credit union Camilla has joined, although she has visited five others in the past three years, and is eligible as a Borough of Westminster resident. She said: "It's very important to get the word out and tell people about it. It is just raising awareness. Probably like many other people I didn't know much about it."
Wendy Powell, 67, was at the branch with her daughter Clare, 32, who is already a member. She said: "I told Camilla I was just here with my daughter but that I was thinking of joining and she said she would as well. I said she should get behind me in the queue."
Louis McLeod, treasurer of LMCU, said: "When you join you're given a share account and encouraged to save on a regular basis. You also have access to various perks that are invaluable in a credit union current account. You also have access to the Isa account. The Duchess would save dividends like any other member on her regular share account and if she did make an Isa account she would get 3% interest. She would be able to take advantage of both the traditional share account and also the Isa account and the current account."
Lucky Chandrasekera, chief executive of LMCU, said the credit union is trying to attract more affluent members. He said: "If everyone is unemployed and can't save money you don't have money to give, so you need affluent people as well. We are now introducing a cash Isa and working on introducing mortgages and we have just finished testing the iPhone app so it's for the younger generation, so we are working on that." LMCU became the first British credit union to offer a payday loan last year and now has more than 16,000 members.