Liam Stanford, 36, of Spendmore Lane, Coppull, Chorley, used his position as an assistant officer at Her Majesty's Revenue and Customs at the Guild Centre, Preston, to falsely alter accounts for 21 people, which enabled them to claim a total of Â£360,000 in tax credits.
Stanford inputed dates and filled in paperwork between 2004 and 2007, to show the defendants or their children were severely disabled, which increased their tax credit payments.
The 22 defendants from across Chorley and the north west, pleaded guilty to section 35 of the Tax Credit Act, at a series of Liverpool Crown Court hearings.
Stanford was jailed for four years, three months and three others were given jail terms during a series of hearings which ended yesterday.
Speaking after the case Ian Horridge, senior manager at HMRC described the defendants as '˜deplorable'.
He said: 'This group has been responsible for a deliberate and sustained attack against the UK tax credits system in a deplorable attempt to defraud a system aimed at supporting the most vulnerable in our society.
'Liam Stanford abused his position, compromising the trust and level of service that the public are entitled to expect from us. HMRC is committed to the highest levels of integrity and we take decisive action against the tiny minority who let us all down by falling short of those standards.'
Officers hope to recover the falsely claimed cash through the Proceeds of Crime Act.
Three other defendants were jailed; Paul Whittle, 37, of Canterbury Street, Chorley, was locked up for 25 weeks.
Paul Hulme, 30, of Finsbury Place, Blackburn was jailed for 21 weeks and Neil Burrows, 43, of The Crescent, Chorley, was sentenced to 20 weeks.
The following were giving suspended jail sentences; Patricia Thompson, 47, of Springfield Road, Coppull; Caroline Lea, 30, of Howard Road, Chorley; Corinne Austin, 49, of Shakespeare Terrace, Chorley; Janet Goodman, 48, of Shelley Close, Coppull; Sharon Burrows, 42, of The Crescent, Chorley; Caroline Whittle, 30, of Canterbury Street, Chorley, Shaun Marsden, 43, of Danesway, Heath Charnock, Robin Taylor, 33, of Arcon Road, Coppull; Louise Mather, 29, of Highfield Avenue, Wigan, Laura Entwistle, 30, of High Street, Oswaldtwistle; Lee Benson, 42, of Preston Road, Coppull; Kevin Shaw, 48, of Wigan Road, Aspull, Wigan; Susan Leonard, 57, of Haigh Road, Aspull; Lynn Thompson, 54, of Wigan Road, Aspull; Alison Howard, 46, of Clancutt Lane, Coppull; Keith Baxter, 30, of Kingsley Avenue, Wigan, Paul Kirfoot, 41, of St Gregory's Place, Chorley and Tracey Nolan, 46, of Mereford, Charnock Richard.
Alison Howard, 51, of Clancutt Lane, Coppull, pleaded guilty to dishonesty. Her conviction was subsequently quashed by the Court of Appeal in April 2012.