Put the issuing authority first
Read the sender, account reference, tax period, and notice identifier before focusing on the amount. Create a distinct cover sheet for the IRS document and the California document. Copy each requested action and response method from the actual notice. Similar words on two letters do not establish that they concern the same process or require the same reply.
Compare the facts behind the letters
Place the relevant return and supporting records beside each explanation. If both letters refer to a related event, note the connection while keeping their individual questions visible. A payment confirmation should show its intended authority and period. Mark unclear entries for review rather than assuming that a transaction appearing in one file answers the other account.
Preserve two readable response trails
When material is submitted, keep the final version, destination, date, and confirmation with the appropriate letter. Add later correspondence to that same trail. If a professional is involved, clarify who monitors each account’s instructions and how new documents will be shared. Check the current IRS and Franchise Tax Board resources as relevant; a general guide cannot establish the response or result for an individual notice.