• We recommend that you keep the previous 6 years returns, documentation, and receipts.  Some people keep a copy of the tax returns older than six years and just destroy the documentation and receipts that are seven years and older.  The IRS can generally audit the previous 3 years tax returns.  However, there are numerous circumstances in which having these additional three years would be to your advantage, especially if you own your own business.  
• MOST IMPORTANTLY, Documentation that will support a deduction or establish a tax basis on a future tax return MUST BE KEPT until the asset is sold.  This refers to your principal residence, mutual funds and stocks, and investments in partnerships just to name a few.  Typically, this means the information must be retained longer than 6 years.
• As a service to you, our client, we will be happy to maintain a copy of this long-term information in our files. In order for us to have complete documentation, would you please send us the following information:

• We would like a copy of the closing statement from the purchase of your home. The closing statement is typically on two long pages.
• We would like a copy of the tax return from the year that you sold your last principal residence.  A Form 2119, Sale of a Principal Residence should be included in that year's tax return.  A lag in time between the sale of one residence and the purchase of another sometimes requires the Form 2119 to be filed in two (usually consecutive) years.  If so, a copy of both returns is necessary.
• We would like a list of any home improvements and the cost to you.  Receipts or other forms of documentation are necessary for the IRS but a list at this time is all that we need.  A home improvement is anything done that extends the life of your home (a new roof, siding) or improves the value of your home (landscaping, planting of trees).

• ALL (from your first purchase to now) year-end statements from the companies which recap your purchases and sales of shares during each year.
• Purchase confirmations from the brokerage houses.

The IRS requires the above documentation to support the net gain reported on the sale of your assets.  The advantage of accumulating this information now is better documentation and therefore, a larger purchase cost and basis for your investments which will result in a lower tax liability in the future.