By Jenny Culshaw
Genuine jobs do not ask for upfront cash, authorities say.
Scammers targeting people who want to work from home are using the downturn in the economy as a chance to cash in, the Office of Fair Trading says.
Firms tricking people into thinking they can earn easy money, cost UK victims £70m a year, the OFT estimates.
And it believes that figure is set to rise during the current recession.
The OFT is highlighting the trend as part of Scam Awareness month which seeks to stop people being conned and parting with their cash.
Last year 209 people reported misleading home working schemes to the government's consumer advice body Consumer Direct but the OFT says this figure is the tip of the iceberg.
"Only 2% of people who get taken in by these scams actually report them," said Mike Haley, Director of Consumer Protection at the OFT.
I'm trying to earn money legitimately and there's someone out there taking my money
"Our research shows that over 300,000 people each year are falling victim and it's on the increase because of the economic climate.
"People are looking for work, for easy opportunities to earn money and these scammers are exploiting that false hope."
Elizabeth Cork from Norfolk was among those to be taken in by such a scam, after spotting an advert in a national newspaper to earn up to £300 a day at home filling envelopes. It asked for a payment of £35 for a starter pack.
"It wasn't too much money so I thought it would be a fairly safe thing to do," Mrs Cork told the BBC.
Initially nothing arrived but after writing to them again, she received an information pack, but no envelopes.
Instead she got instructions to place leaflets - including her contact details - around her village. She was told that when people got in touch, she would then receive £1.70 in return for passing their details to the company.
Mrs Cork contacted Trading Standards who told her to write again and demand a refund or the work she was expecting. Almost two months on, she has heard nothing back.
The golden rule is if it sounds too good, it probably is
"I feel really annoyed," she said.
"It's the fact I'm trying to earn money legitimately and there's someone out there taking my money."
The traditional method of advertising such schemes is by pinning notices on lampposts and by direct mail.
However, they also appear alongside genuine job opportunities in newspapers, shop windows and online.
"The golden rule is if it sounds too good, it probably is", says Michele Shambrook from Consumer Direct.
"A genuine job is highly unlikely to ask you to pay any money upfront or any registration fee."
She added that commonly-seen schemes ranged from envelope stuffing to being asking to put together kits, which then got rejected for poor quality and for which you never received payment."
Consumer Direct suggests anyone looking for home working opportunities should contact their local job centre.
Their advice to anyone who thinks they have been drawn into a home working scam is to contact them at www.consumerdirect.gov.uk or 08454 040 506.
A report on this can be seen on the BBC News Channel on Saturday 7 February