One transaction can have several date fields
A property transaction can produce an instrument date, a recording date and later publication in an agency dataset. The site’s release date is another event: when the source material was assembled for this product. These dates should not be collapsed into one generic ‘sale date’ without checking the field definition.
The Illinois transfer declaration asks for the month and year from the instrument. A dataset may separately record when the declaration or instrument was recorded. Field labels and source documentation determine which event a displayed date describes.
Sources: IDOR: PTAX-203 form and instructions
Reconcile records using more than a date
Compare the PIN or set of PINs, the instrument, disclosed consideration and available record identifiers. Differences in timing are a reason to inspect the original records; they are not automatically evidence of two sales, an error or a suspicious transaction.
Cook County Records displays Assessor sale history and IDOR MyDec declarations separately because they are different source systems. Where a field is unavailable, keep it unavailable. Do not manufacture an exact day from a month-only source or silently substitute the site’s release date.
Preserve the timeline in an export or citation
Give each date its own column: source event label, event date, agency publication date and site release date. Link both sources and describe whether the relationship is confirmed or only a candidate match. This makes an apparent discrepancy reviewable later.
When reporting a recent-sales trend, state which date controls inclusion in the period. A transaction recorded later can move into a different reporting period even when the underlying instrument is older. The scope and timestamp should travel with the chart or CSV.