The target date will vary depending on the type of assessment, but it is similar to a service date. It reflects the time frame in which the assessment was to be completed. Researchers often pull MDS data by target date because it is likely to be closer to when the assessment occurred.
The submission date is simply the date that the assessment was submitted to CMS and does not reflect the date when the assessment was actually completed. Researchers often pull by submission date when they want to be sure to capture all assessments, including any corrections to previously submitted assessments.
The target date and submission date are always populated on the MDS assessments. There are no missing data for these fields.