He has so far received half of that figure and has agreed the balance should be paid in four instalments at six-month intervals.
O'Leary's successors at Elland Road, Terry Venables and Peter Reid, are reportedly receiving their pay-offs weekly.
"I've got a lot of affection for Leeds," O'Leary said. "I am sorry to see the club is in such a mess financially and am happy to do anything to help.
"I'd be hurt financially if the club goes into administration," O'Leary added. "And so would quite a number of others."