  We investigate the twist-$3$ transverse-momentum-dependent parton
distribution functions (TMDs) of the pion with basis light-front quantization.
The twist-3 TMDs are not independent and can be decomposed into twist-$2$ and
genuine twist-$3$ terms from the equations of motion (EOM). We compute the TMDs
from the resulting light-front wave functions obtained by diagonalizing the
light-front QCD Hamiltonian, determined for pion's constituent quark-antiquark
and quark-antiquark-gluon Fock sectors, with three-dimensional confinement. We
also obtain the twist-3 parton distribution functions (PDFs) and show that they
preserve the sum rule, which affirms the robustness of our approach. This is
the first time that theoretical predictions are made for subleading twist
structures of the pion containing interference terms between two light-front
Fock sectors.
