The team owe him 17.15m euros (£14.5m) because of a salary of eight million euros and a bonus scheme worth 50,000 euros a point.
Hulkenberg will now drive for Force India, where sources say his deal has been done.
He is expected to be joined by Mexican former McLaren driver Sergio Perez, who is on the verge of concluding his own deal with Force India.
Born: 19/08/87, Emmerich am Rhein
Career wins: 0
Career pole positions: 1
2013 points total: 51
Hulkenberg's Sauber seat will be taken by German Adrian Sutil, whose contract is also said by sources to be secured but has not yet been announced.
The identity of the Swiss team's second driver is not yet known, but they are likely to stick with Mexican Esteban Gutierrez for a second season.
This year's other Force India driver, Scot Paul Di Resta, will lose his place in F1 and is hoping to land a seat in US-based IndyCar racing.
Lotus is a major step up for 28-year-old Maldonado, who won one race for Williams in Spain in 2012 but whose driving has often been erratic.
He has made it clear that he felt Williams had held him back this season, while the team were also happy to part company. Williams have
signed ex-Ferrari driver Felipe Massa
to join promising Finn Valtteri Bottas.
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