This document compares guidelines from seven organizations - ATA, ESMO, BTA, NCCN, SNM, EANM, CSE/CSS/CACA/CSNM - for 131I remnant ablation in patients with differentiated thyroid cancer. While all organizations define ablation as eliminating the thyroid remnant, some guidelines incorporate additional treatment of microscopic tumors and metastases. Indications vary between guidelines and there is controversy around management of low risk patients. More evidence is needed to standardize risk stratification and guidelines. The NCCN emphasizes diagnostic imaging prior to 131I administration to target uptake in the thyroid bed. Overall guidelines are becoming more standardized with improved terminology and evidence.