No "thumbs up" here for the responses I received on turning off the seat belt chimes. Here's the way it's done with a warning from Subaru:
To permanently disable this warning chime:
After turning the ignition switch ON, repeat fastening and unfastening the driver's seat belt for 20 times within 30 seconds.
Enabling and disabling this cutoff feature is done with the same operation. This setting is changed for both the driver's seat and passenger's front seat. This setting lasts until the microprocessor is reset. The disabling function is reset when the car battery is removed and/or when the body integrated unit is removed. The disabling function may also be reset when the engine is cranked with low battery voltage.
Since seat belt usage is the single most effective action that an occupant can take to reduce the risk of injury or death in a motor vehicle collision and safety is one the highest priorities at Subaru, 2005 Legacy and Outback vehicles (and future Subaru vehicles) have a belt reminder system for the front driver and passenger seats. This belt usage monitoring and reminder system is incorporated in Subaru vehicles with advanced airbag systems.
While there may be valid reasons for either temporary disabling the belt reminder system, Subaru does not encourage use of the permanent disablement feature. Not using the seat belt can increase the risk of injury or death in front, side, rear, rollover, etc. collisions and reduce the effectiveness of inflatable restraints ('airbags') because of out-of-position occupants. However, the final decision in such a matter resides with the vehicle owner.
Owners who permanently disable the belt reminder feature should reset the reminder system as soon as possible, especially if the vehicle is sold.