Darren Challis, 33, was released from his 18-month prison term in November 2013, after being jailed for diverting Self Assessment tax repayments from unsuspecting clients of an accountancy firm where he worked as an administrator, into his personal bank account.
But four months after his release, he registered with HM Revenue and Customs (HMRC) as a self-employed building contractor.
Investigators found he manipulated four tax returns, two in his own name and two in the names of close friends.
He made 36 fraudulent amendments to the returns between April 2014 and January 2015.
When HMRC officers arrested Challis in August 2015, he confessed to the fraud.
Richard Young, Assistant Director, Fraud Investigation Service, HMRC, said: “Challis showed no regret for his crimes as within months of walking out of prison, he was back stealing taxpayers’ cash, determined to get his hands on money that should have been funding vital public services.
“He clearly had a total disregard for the tax system, but now back behind bars, he has time to reflect on the risks of getting involved with tax fraud rather than the benefits he had hoped for.
“Anyone with information about individuals or businesses committing tax fraud can contact us via our 24-hour hotline on 0800 59 5000.”
Challis pleaded guilty at an earlier hearing and was sentenced to 12 months jail when he appeared at Lincoln Crown Court.
HMRC will now seek to recover the proceeds of his criminal activity.