How do I calculate new tax basis on 1031 exchange property acquired in 2005?

You will find the basis of the acquired properties in Part III, line 25 of the 8824 that was filed with your return in the year of the exchange.  You should also have a depreciation schedule for these properties in your prior returns showing the basis.  If you cannot locate any of these forms in your prior returns, you should call your accountant and ask for them. Trying to calculate basis after all this time could be very difficult, because it depends on all the data he entered on the 8824 back then, also the basis and Fair market Value of the former and current assets at the time.