Assuming "there" means "their" and you are working on a joint return, it's quite possible that no 1099-S was issued because the sale was for less than $500K and the taxpayers certified that the home had been their primary residence for two of the last five years.  it's also quite possible that their closing documents included a copy of the certification form they signed.  So the place to start is by asking (or looking) for that, to avoid needless paperwork.  Unless you really want to run up the bill.