In "Revenue Ruling 2008-5", the IRS explained that when shares are sold in a non-retirement account and substantially identical shares are purchased in an IRA within 30 days, the investor cannot claim tax losses for the sale, and the basis in the individual's IRA is not increased.
https://www.irs.gov/pub/irs-drop/rr-08-05.pdf
As @Rick19744 explained previously, the problem is avoided if you wait 31 (or more) days between the transactions.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
