I'm creating an invoicing schedule and so my primary column is a list of tasks and then I have columns for past, current and future months: Dec-20, Jan-21, Feb-21, Mar-21, Apr-21 etc. In the cells I enter a monetary value which is the amount we either have invoiced or plan to invoice.
I want to have a column (Invoiced to Date) which adds up the invoicing amounts in a row, but does not include the current month or beyond, but cannot find a way to reference the actual column name. Is this possible?