There is a penalty for failing to file the Form of List pursuant to M.G.L. Chapter 59, Section 64. If you do not file a Form of List for the fiscal year, the assessors cannot grant an abatement. If you show a reasonable excuse for filing late, the tax assessed cannot be reduced lower than 150% of the amount that would have been assessed if the list had been timely filed. In that case, only the amount over that percentage can be abated. You can avoid this penalty by filing on time.