  We report on progress toward computing a four-loop supersymmetric form factor
in maximally supersymmetric Yang-Mills theory. A representative example
particle content from the involved supermultiplets is a stress-tensor operator
with two on-shell gluons. In previous work, the integrand for this form factor
was obtained using color-kinematic duality in a particularly simple form. Here
the result of applying integration-by-parts identities is discussed and
cross-checks of the result is performed. Rational IBP relations and their
reduction are introduced as a potentially useful aide.
