After electronically filing 2017 using TurboTax,  I received  a revised 1099 OID citing increased Original Issue Discount and filed an amended return which I had to  submit by mail and pay a tax difference.  After filing that amended return, and somewhat late in the process, I received yet another revised 1099 OID.  However, this time the Original  Issue Discount was now about $160 less than the first revision.  I did not refile an amended return to the recognize this reduction.  My question is two fold.  Am I required to file and an amended return as this would likely slightly reduce my tax liability for that year?  If I am not required to file,  would it be worth it to file another amended return for such a small amount?