6d, N = (1,0) Coulomb branch anomaly matching

6d QFTs are constrained by the analog of 't Hooft anomaly matching: all anomalies for global symmetries and metric backgrounds are constants of RG flows, and for all vacua in moduli spaces. We discuss an anomaly matching mechanism for 6d N = (1,0) theories on their Coulomb branch. It is a global symmetry analog of Green-Schwarz-West-Sagnotti anomaly cancellation, and requires the apparent anomaly mismatch to be a perfect square, Delta I-8 = 1/2 X-4(2). Then Delta I-8 is cancelled by making X-4 an electric/magnetic source for the tensor multiplet, so background gauge field instantons yield charged strings. This requires the coefficients in X-4 to be integrally quantized. We illustrate this for N = (2, 0) theories. We also consider the N = (1, 0) SCFTs from N small E-8 instantons, verifying that the recent result for its anomaly polynomial fits with the anomaly matching mechanism.