You are completely correct.  The budget is used ONLY to set the current year's assessment.  Once agreed and passed it becomes completely useless.  Our governing documents specifically allow for change.

The comparisons we make are likewise worthless.  Comparing one guess with another provides no information other than maybe the quality of the guesses.

I prefer comparison of current actual to prior actual(s).  By doing this one is comparing facts to other facts.  In addition, the audited Association statements provides a sanity check of sorts on our reporting.

I might even support a change to base the assessment on last year's actual results with a separate step to remove things no longer needed and add an identified guess at future needs.  Since the budget can be changed easily, the risk to us of missing something is low.

Jeff