In my 2012 tax return I received a qualified dividend. In July of 2013 I received an amended 1099-DIV that reclassified the dividend to return of capital. I did not refile an amended CY2012 1040 tax return. In 2015 I sold said shares and my 1099-B (form 8949, PartII with box E checked) has a different cost basis for those shares than my calculation. The difference is traced back to the July 2013 amended 1099-DIV. Do I have to file an amended 2012 tax return to get everything back in sync, or can I just override the brokerage download cost basis and force it to match my calculation even though the brokerage reported amount is what the IRS has? Thanks for your insight.
