  Floquet topological phases emerge when systems are periodically driven
out-of-equilibrium. They gained attention due to their external control, which
allows to simulate a wide variety of static systems by just tuning the external
field in the high frequency regime. However, it was soon clear that their
relevance goes beyond that, as for lower frequencies, anomalous phases without
a static counterpart are present and the bulk-to-boundary correspondence can
fail. In this work we discuss the important role of resonances in Floquet
phases. For that, we introduce a method to find analytical solutions when the
frequency of the drive matches the band gap, extending the well-known high
frequency analysis of Floquet systems. With this formalism, we show that the
topology of Floquet phases can be accurately captured in analytical terms. We
also find a bulk-to-boundary correspondence between the number of edge states
in finite systems and a set of topological invariants in different frames of
reference, which crucially, does not explicitly involve the micromotion. To
illustrate our results, we consider a periodically driven SSH chain and a
periodically driven $\pi$-flux lattice, showing that our findings remain valid
in different systems and dimensions. In addition, we notice that the
competition between rotating and counter-rotating terms must be carefully
treated when the undriven system is a semi-metal. To conclude, we discuss the
implications to experimental setups, including the direct detection of
anomalous topological phases and the measurement of their invariants.
