Causey, the company's former chief accounting officer, pleaded guilty in December to securities fraud two weeks before he was to be tried along with Enron founder Kenneth Lay and former chief executive Jeffrey Skilling on conspiracy, fraud and other charges related to the company's collapse.
Causey, 46, had agreed to serve seven years in prison. Prosecutors indicated they could have recommended it be reduced to five if they were pleased with his cooperation.
The maximum penalty for securities fraud is 10 years in prison and a fine of $1 million or twice the amount illegally gained.
Causey also agreed to fork over $1.25 million to the government and forfeited a claim to about $250,000 in deferred compensation as part of his plea deal. Unlike others at Enron, Causey didn't skim millions of dollars for himself from shady deals.
Prosecutors dropped their pursuit to seize Causey's home, a $950,000 two-story, red brick house in a Houston suburb.
Causey, the government's 16th cooperating witness to enter a guilty plea, had faced more than 30 counts of conspiracy, fraud, insider trading, lying to auditors and money laundering.
In his guilty plea, Causey admitted that he and other senior Enron managers made various false public findings and statements.
He did not testify in the Lay-Skilling trial earlier this year, though he was on the defense witness list.
Skilling and Lay were convicted in May of conspiracy and fraud. Lay's convictions were wiped out with his July death from heart disease. Skilling was sentenced last month to more than 24 years in prison.
Andrew Fastow, Enron's ex-chief financial officer whose schemes helped doom the company, was sentenced in September to six years and is serving his term in a federal prison in Louisiana.
On Friday, Mark Koenig, Enron's former investor relations director, and Michael Kopper, an Enron managing director and Fastow's once-trusted top aide, were set to be sentenced.
Enron, once the nation's seventh-largest company, crumbled into bankruptcy proceedings in December 2001 after years of accounting tricks could no longer hide billions in debt or make failing ventures appear profitable. The collapse wiped out thousands of jobs, more than $60 billion in market value and more than $2 billion in pension plans.