one may be using formula one may be using IRS depreciation tables. in this case, the difference should be small. Other reasons include one is using bonus or section 179 depreciation. the other is not. it might be QB is using book depreciation which can be completely different than tax depreciation. it's also possible a different life or method was selected for one or the other. you provided no information as to cost, date placed in service, type of asset, depreciable life, method and whether bonus or 179 were selected so the exact reason can't be stated.
you can not override the TT calc unless you want to file by paper. I not saying TT is right and QB is wrong only that TurboTax by design voids its accuracy guarantee if overrides are used and won't let you e-file.
