My crypto cost basis changes when I use "shares transferred between accounts"

Question

Was looking at my cost basis for crypto and noticed the cost in the "Removed" entry is different than the cost in the "Added" entry for the same transaction.  Example: Bought 0.0055 shares of Bitcoin at 89,209.09, with a $9.20 fee.  Total is $499.85.  When I transfer the shares to another account, the Removed txn shows $499.85 (correct), but the corresponding "Added" txn show $500 for cost basis.  And due to that the Price is different as well.  I understand the price will reflect the $9.20 fee, so it should be $90,881.82 (499.85/0.0055).  But the price is $90,909.090909.  When I transferred the shares back and sold them, the capital gains was based on the $500, not $499.85.  Yeh, good for me but I don't think the IRS will be happy.

I recreated the same price/cost basis difference in a new Quicken file so it's not related to different accounts or how much is already in an account.  It was the first Bitcoin purchase in the account.  Anyone know why the cost basis is different?  I tried a stock purchase and it kept the same cost basis after the transfer.  I even did a stock buy with 11.0055 shares just to see if the extra decimals was the issue.  Kept the same cost basis.

Tom Young · Accepted Answer

In a test file I transferred 0.008292 Bitcoin at a cost of $490.80 to another Account and the cost came over as $490.83, so obviously the program isn't simply "moving" the shares and cost from one Account to the other, there's some behind the screens calculation going on, with a new cost basis being the result.  A floating point number problem would be my guess.  As someone who's a non-programmer I don't understand why the program throws in what appears to me to be a non-necessary calculation, losing precision along the way, but really it's immaterial.