Alright so now that the IRS has sent you the changes to your 2010 income tax return because you did fail to correctly report the sale of the mutual fund securities using the information that you did have available to you after the end of the 2010 tax year that was reported to you and to the IRS on the Mutual fund consolidated 1099 and the 1099-B information for this purpose.
So now you will have to fill out and file a 1040X for this purpose using the 2010 schedule D and the instruction that are available for your use line by line using the www.irs.gov website search box for this purpose.
Use the search box at the www.irs.gov website for Prior Year Products
http://www.irs.gov/app/picklist/list/priorFormPublication.html
Prior Year Products
Use the box FIND and TYPE 1040 and choose PRODUCT NUMBER click on SEARCH and then choose the 1040 tax year form and the instructions that you will need for your use at this time in your life.
http://www.irs.gov/app/picklist/list/priorFormPublication.html?value=1040&criteria=formNumber&submitSearch=Find
Check our the pages of the 1099-B to see if you can FIND any cost basis listed for any of the securities that were sold during the tax year 2010 for this purpose.
Check with the payer of the funds to see if they can help tp determine any kind of cost basis with some written proof for this purpose.
When the taxpayer is unable to establish prove the cost basis then the IRS will assume that the cost basis is -0- ZERO at that time in your life.
Use the search box at the www.irs.gov website for the Instructions for Form 1040X (12/2011)
http://www.irs.gov/instructions/i1040x/index.html
Lines 1 - Through 31—Which Lines To Complete
http://www.irs.gov/instructions/i1040x/ch02.html#d0e645
Before looking at the instructions for specific lines, the following information may point you in the right direction for completing Form 1040X.
Payments and refundable credits Lines 10–22
You are changing amounts on your original return or as previously adjusted by the IRS. Because Form 1040X can be used for so many purposes, it is sometimes difficult to know which part(s) of the form to fill out. Unless instructions elsewhere in this booklet tell you otherwise, follow the rules below.
Always complete the top of page 1 through Amended return filing status.
Complete the lines shown in the following chart according to what you are changing.
Check a box in Part II, if applicable, for the Presidential Election Campaign Fund.
Complete Part III, Explanation of changes.
Sign and date the form.
Hope that you find the above enclosed information useful. 08/08/2012