Patrick Gerard Small and Mary Elizabeth Small failed to declare tax worth £4.6m over a period dating back to 1995. The case against them was the largest case of its kind to come before the Crown Court in Northern Ireland.
Belfast Crown Court judge Anthony Hart jailed Patrick Small for three-and-a-half years and Mary Small for two-and-a-half years, saying of Mr Small: "He was prepared in a dishonest and unedifying fashion to shift as much of the blame onto his wife as he could."
The couple used an offshore bank account in the Isle of Man and laundered money through property developments in order to dodge their taxes, building 23 houses in Northern Ireland, which remained empty, as well buying valuable antiques and jewellery.
A search of the Smalls' main property recovered over £492 000 from safes that had not been declared as income.
Investigators uncovered a recording of Small meeting a Manx bank official in 2004.
In it, he told the banker he was aware of the taxman, adding: "I told him nothing, I told him I had not a penny about whatsoever."
An HMRC spokeswoman said: "Anyone deliberately setting out to cheat the system by not paying the right amount of tax is taking a huge risk, as we will pursue and bring them to justice."
It has also emerged the couple continued to claim tax benefits during the fraud.