Janet Roberts, grants manager at the HBOS Foundation, said funders preferred joint bids because they got a "real return on investment".
Sarah Hooker, deputy development director at YouthNet, said her charity had raised £7.5m in the past year through collaborative fundraising - a much larger sum than the charity could have raised on its own.
Citizens Advice provides debt advice for young people on the YouthNet website TheSite.org. The partnership received £300,000 from the HBOS Foundation.
Hooker said potential partners should have open conversations about responsibilities and be clear in advance how much funding each partner will receive if bids are successful.