Differential equations are one of the main approaches to evaluate multi- loop Feynman integrals. The construction of a canonical or ε-factorised basis for multi- loop integrals remains a key bottleneck for this approach, especially when the differential equation involves non dlog-forms. Recently, several methods have been proposed to find ε- factorised differential equations. Many of them introduce new functions that are themselves defined as iterated integrals. If and when these iterated integrals can be explicitly evaluated in terms of other classes of functions remains an open problem. We elaborate on the recent proposal that one can use the fact that the intersection matrix computed in a canonical basis is constant to derive polynomial relations between these iterated integrals.