Can I legally change the cost basis of shares sold and reported on 1099-B, Form 8949, Part II with Box D checked?

[bce0]

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.

[TomYoung · Accepted solution]

Well of course you can change the basis reported by the broker, even if the broker is reporting the basis to the IRS.  Brokers are not infallible, though in my experience they come pretty darn close. 

In the overall, you over reported your 2012 income and will correctly report your gain in 2015 with your adjustment, so you are in a net over reported situation and it's up to you if you want to amend 2012.  Unless you are talking about an absolute ton of money I expect the IRS will never question your change.  They probably only see a few million changes every tax year.

Tom Young

[bce0]

Thanks Tom, great info much appreciated.