To display what should be row based data in a column format in a report, I'd say you will need to base the report on a crosstab query. However, AFAIK the query fields have to be made static,otherwise errors will be raised when certain months don't have values (the report controls will be "looking" for them. Nor can you design such a report with 12 fields for months and only show say, the 1st, 3rd and 5th. Also, whatever decision logic that determines which columns are totaled would be for you to decide? In any event, I doubt you will ever come close to arriving at such a report without any code. Maybe if you stack 12 month controls in one spot in report design you can use code to
a) show only the controls for the months found in the query sql
b) make visible and position the ones you need and hide the rest
c) but only if you have a form where the user constructs the sql on the fly and you use that to "design" the report.
This sounds like Access might be the wrong tool for the job because it's designed for relational row based data, not column based like Excel. If you're new to the application, I think you will find this to be a bit of a challenge. Maybe look here for schemas for membership dues databases.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.