  We investigate the nonclassicality of a two-level system driven by an
external time-dependent field in the presence of dephasing. We consider two
criteria for nonclassicality, one based on the quantum witness built upon the
no-signaling in time condition and one based on the temporal steering
inequality, for a linearly driven qubit. We show that both strongly depend on
the amplitude of the driving field. As a result, we demonstrate that the
quantumness of the two-level system can be successfully controlled by properly
tuning the driving strength. We establish in particular that maximal violations
of classicality allowed by dephasing can be achieved at arbitrary chosen times.
