Choose a starting date
Write down the date the opening position represents. Avoid mixing a bank balance from one day with customer balances from another. A shared starting date gives subsequent activity a consistent reference point and makes differences easier to investigate.
Identify the source of each balance
Use the prior closing records, relevant statements and supporting schedules. Note who prepared them and whether unresolved adjustments remain. An opening figure copied from a spreadsheet without context may look precise while still being incomplete.
Separate open items from totals
A customer total is more useful when the outstanding documents behind it can be identified. Keep payments and credits attached to the same review. Check whether an item was already settled before carrying it forward into the new period.
Record unresolved differences
Do not bury a difference in an unexplained adjustment. Keep a short note describing the two sources, the amount and the next investigation step. Your accountant can help determine the appropriate treatment. Preserve enough context for another person to reproduce the comparison.