I have had the same problem for years with TT when donating appreciated mutual funds. I am using the fair market value of the donation at the time of the donation. They have all been held for many years (not less than 1 year) but TT always reverts the value of the donation to the cost basis as soon as that is entered. The only way I can get around it is to change the cost basis to the current value on the date of donation.
I am not sure but wonder if it might have something to do with the option the IRS gives that we can deduct 50% of the value of the basis of the donated stock instead of 30% of the FMV at the time of the donation.
