The fraud involved David Reid, from County Durham, advising people to put money in an offshore account, but it emerged the account did not exist. The police began inquiries into Washington Mortgage Centre last year after receiving a number of complaints and he was arrested last March.
Reid pleaded guilty to 23 counts at Newcastle Crown Court.
Det Ch Insp Christina Barrett, of Northumbria Police, said:
"He deceived people out of millions of pounds and left many of his victims suffering significant financial hardship.
"These people put their trust in Reid and his actions are nothing short of disgusting. The impact on these individuals cannot be underestimated with generations of families' inheritance stolen by Reid."
She said it had been "a long-running and complicated investigation".
