2020
A tax officer files a return.
He reconciles it the way he thinks is right, notes an adjustment in a spreadsheet on his laptop, and moves on. He is not careless. There is simply no standard for how this should be recorded.
2021
He leaves. A new officer joins. Nothing is broken, nothing is overdue, no one is asking about 2021. So he does what any reasonable person would do. He leaves it alone.
2023
He leaves too.
2024
The audit notice arrives, and it is about 2020.
The officer now holding the file has never seen that return. He reconstructs the story from what he can find and submits it in good faith. The authority does not accept it. A notice of discussion follows.
A consultant is brought in. He spends weeks rebuilding a trail that was already built once, three years ago, by someone who no longer works there. He does good work. It is late.
Then the CFO asks the only question that matters. Are we alright? Can I trust you have this?
Nobody in the room knows.
Not because anyone failed. Every person in this story acted reasonably. But the reasoning behind a 2020 position lived in one man's head, his laptop, and an email thread nobody can find. He has been gone for three years.
____________
This is not an unusual story. It is the normal life of a tax event in most organisations. The judgement, the evidence and the intent all live in people, and people leave.
__________
The cost is not the reconstruction time. It is the assessment you cannot defend, because you cannot prove what you actually did
Setoff exists so that a tax officer steers the record instead of carrying it. The position, the reasoning, the evidence and the correspondence sit in one system of record, attached to the period they belong to. When the notice arrives, the answer is retrieved, not rebuilt.
The system memory outlives the staff. A CFO stops operating on trust and starts operating on knowing. Because what happened in 2020 should not depend on whether one person is still with the company.