Yes, under FAA regulations (specifically 14 CFR §1.1), a pilot can log taxi time as part of their "Flight Time." The FAA defines flight time as beginning when the aircraft moves under its own power for the purpose of flight and ending when the aircraft comes to rest after landing. This means that from the moment you release the brakes and start the engine-driven taxi toward the runway, you are officially accruing flight hours. This is why many pilots and flight schools use the "Hobbs Meter" (which runs whenever the engine is on or the master switch is engaged) to record their time. However, if you are just taxiing the plane to a maintenance hangar or a different parking spot without the intent to fly, that time cannot be logged as flight time. For commercial and airline pilots, this "block-to-block" time is the standard metric used for both their legal flight logs and their paychecks.