Students are being targeted in holiday job scams including one whose family was conned out of £10,000.
Fraudsters are posting fake adverts on job sites and some have deliberately posed as families looking for a nanny, according to charity Crimestoppers.
On average victims and their families caught up in the cons lose around £4,000, and in one case a student's parents lost £10,000.
Awareness scheme SAFERjobs has seen employment scams worth £423,773 reported in the past year.
A total of 805,349 people have contacted the initiative in those 12 months, many reporting suspicious activity which meant fraud could be prevented.
SAFERjobs chairman Keith Rosser said: "The students who seem most vulnerable are those in their first year at university.
"They're trying to demonstrate to their parents that they can be independent and earn on their own.
"But it's not just the students who suffer. In a lot of cases, they're borrowing money from their parents. We dealt with one case where a couple had lost £10,000 to a scam.
"We've even had families contacting us because they need help trying to explain to their offspring that they're being scammed. Some victims just can't be persuaded because they're so desperate to make it on their own."
Some of the cons include victims paying out for a service; for example, a fake criminal records check or childcare training course.
Scammers have posed as families looking for a nanny on genuine sites, and then demanded that a recruit pays in advance for travel and visas which never materialise.
Other frauds involve work from home offering an unusually high salary, which ends with victims unwittingly laundering money by cashing cheques or buying office supplies for their employer.
Another involves a premium rate line, which could see victims billed for £500 per hour on the phone as they think they are having an interview.
According to SAFERjobs figures, the highest value of fraud was reported in July and December last year.
In December 2015 and January 2016, 38% of victims in job scams were students.
One victim, who did not want to be named, said: "They told me that I needed to perform a DBS (criminal records) check and gave me a link where they asked me for 100 GBP to have it in time for the start of my job.
"When I tried to explain that it really was suspect, they told me that it normally takes at least two weeks and a lot of people have used this service and it is fine."
Another said: "I was offered a job without interview and all communication done on the internet via email.
"They requested money for DBS checks and informed me that if this was not completed then the job would be revoked. They refused to answer landlines or any email when they were questioned."
Adrian Tudway, head of operations at Crimestoppers, said: "We hope that raising awareness of these scams will help to prevent more young people becoming victim.
"We also want to encourage anyone with information about those committing scams to speak up.
"If you have information, you can contact Crimestoppers anonymously on 0800 555 111 or through our website Crimestoppers-uk.org."