Can an IRA purchase affect a loss I claimed after selling the same stock in a taxable account?
Yes. IRS Revenue Ruling 2008-5 addresses a taxpayer who sells stock or securities at a loss and has an IRA or Roth IRA acquire substantially identical stock or securities within the 30-day period before or after the sale. In that situation, the ruling treats the loss as disallowed.
The ruling also says the IRA or Roth IRA basis is not increased by the disallowed loss. The result still depends on the replacement property being substantially identical and on the actual transaction dates; it should not be assumed for every pair of funds.
