Need Help using Index Match to Merge Datasets accross Multiple Sheets

I have a question in regards to Excel. I have a file with 6 tabs. 4 of the tabs have a code and description of the code. The four tabs are different things, location, type of service, department and store leader. The other two tabs have like invoice amount was and how much was paid on the invoice. What the two tabs have also is some variation of the codes that were in the first two tabs. I have solved the problem using vlookup, but I want to find another method of doing it, using index match to merge the data sets together and sumif if they meet certain criterias. I have never used index match that much, but I have been told it's more powerful than vlookup and doesnt use as much excel space. I will give you an example.

1st tab has

Column A Column B Column C
Invoice # State Code Store Leader code

2nd tab has

Column A Column B Column C Column D Column E Column F
Invoice# # of invoices with the invoice# Type of Service Code Dept Code Invoiced Amt Paid Amt
(Could have multiple invoices with same invoice#)

3rd Tab has

Column A Column B Column C
Type of Service Code Description of Service Service Taxed or Tax Exempt

4th tab has

Column A Column B
Store Leader Code Store Leader Name

5th tab has
'
Column A Column B
Dept Code Dept Name

6th tab has

Column A Column B
State Code Name of State

I want to merge everything into one data set using Index Match instead of Vlookup, but then I have to do a sumif the number of invoiced amount from certain store leaders in the three most populous state, CA, NY and TX who provide a specific service in these three states.

Then I need to sumif tax exempt services that were rendered by store leaders that are not from those 3 states, where taxes were accidentally charged. I am trying to break those down to states, number of invoices and the total paid.

I did this with vlookup and used a pivot table to determine this, but as the information becomes larger that might cause issue with my storage spaced.

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