For ν ∈ [0, 1] and a complex parameter σ, Re σ > 0, we discuss a linear inhomogeneous functional difference equation with variable coefficients on a complex plane z ∈ C:where Ω(z) and F(z) are given complex functions, while a 1 and a 2 are given real non-negative numbers. Under suitable conditions on the given functions and parameters, we construct explicit solutions of the equation and describe their asymptotic behavior as |z| → +∞. Some applications to the theory of functional difference equations and to the theory of boundary value problems governed by subdiffusion in nonsmooth domains are then discussed.