Begin with the notice explaining the difference
Locate the communication relevant to the amount rather than inferring the cause from a smaller deposit alone. Identify its sender, tax period or account reference, explanation, and any stated action. The official source matters because different account events can require different questions and contact routes.
Compare the expected and recorded figures carefully
Keep the filed return and the record of the amount received beside the explanation. Label dates and periods so a different year’s balance is not silently mixed into the comparison. If a line remains unclear, describe the precise discrepancy and identify the record that could clarify it. A working register should show uncertainty instead of replacing it with a confident guess.
Follow the process for the actual issue
Use the current official guidance and the communication’s instructions to determine where the question belongs. If assistance is proposed, ask which account record would be examined and how the work would be scoped. Retain the evidence and any response supplied through a confirmed channel. This guide does not decide why an individual refund changed or promise that the original expected amount can be restored.