Base Maintenance Question

[Nethog]

My Starbase remote mining bases have a cost of 43500 minerals, 600 Organics, and 4600 Radioactives, but their maintenance is listed only as 3262 minerals, 44 Organics, and 344 Radioactives. This appears to be too low, according to my calculations the mineral maintenance should be:

Minerals 43500 X 0.25 X 0.5 = 5438
Organics 600 X 0.25 X 0.5 = 75
Radoactives 4500 X 0.25 X 0.5 = 563

I am playing with a standard 1.49 installation as Cue Cappa. The starbase abilities screen shows a +5% maintenance resuction and a +5 Maintenance increase whuch thus cancel each other out.

Does anyone know the reason for this discrepancy?