get Year-to-Date by hlookup ???

[calimero]

good afternoon everyone,
i hope everyone is doing well


well recently i have been trying to solve an excel issue, for which i hope i can get some help

i have a combo box where users can select the month.
on the basis of the month selection i am doing "hlookup" to return the data value as per that selection.

the problem i have is how to calculate the "rolling Year_To_Date sum" based on the combo box month selection

for example if the combo box selection is May, i need to calculate the sum from January to May; if than, selection changes to "June", i need to calculate the sum from January to June

the only limitation to the solution is that i have to use the hlookup formula to grab the data result for the month selection

i have attached an Excel file for better illustration

Than you in advance for your help

cheers,
calimero