We don't have "drain assessments" and if we did they would be handled by one of the government entities that would enter an assessment for that "pending " project- as an example, they record curb and gutter special assessments in land records, but they are recorded as a probable assessment- and the final assessment is recorded when the project is done- so we would be given an approximate cost per lot/pcl before the project was begun and then a final cost  after it was completed, so notice is given f a pending fee due. The only possible supplemental assessment that would not be known before it it was posted would be supplemental taxes, and since they are all due on Dec 5th of each year, it is pretty  easy to work that out.
Hope that helps you understand how a "good" system works. Remember, our on line systems have "everything" available to us just like in the record rooms, so if you could do it in the clerk's office, we can do it on line if we are a subscriber.
Steve Meinecke
Franklin, Tn