Why your books should be an immutable ledger

The single most important property of trustworthy books is this: once something is posted, it can't be silently changed. Corrections happen by recording a reversing entry, not by editing history. That's what makes the books auditable — anyone can see what happened and how it was fixed.

Editing history breaks trust#

If a posted transaction can be quietly edited or deleted, your financial statements become a snapshot of the current state of a mutable database — not a record of what actually happened. Auditors and reviewers expect a complete trail, and so should you.

This is why mature accounting makes deletion of posted records rare or impossible. The correct move is to reverse: the original stays, the correction is added, and the net effect is right. Two things survive that an edit would have destroyed — the fact that the original entry existed, and the fact that someone decided to change it.

What a correction actually looks like#

Say a $1,200 software subscription was booked to the wrong expense account. The fix is not to open the entry and change the account. It's to post a second entry that undoes the first, with every side swapped:

Account	Debit	Credit
2100 · Accounts Payable	1,200.00
6100 · Office Expense		1,200.00
Total	1,200.00	1,200.00

Then the correct entry is posted normally. The general ledger now shows three entries where a mutable system would have shown one — and that is the point. The history reads as a narrative: this was booked, this was wrong, this is the fix.

How Comma enforces it#

Comma is a real double-entry ledger, and the rules are enforced where they can't be worked around:

• Debits and credits must balance before an entry is written. An unbalanced entry is rejected outright — not flagged for later, not saved as a draft with a warning.
• Posted records are never edited in place. Invoices, bills, payments and journal entries are corrected by posting one linked reversal that swaps every side exactly. The original is marked reversed; both remain in the books and net to zero.
• A reversal can't itself be reversed, and a posted entry can't be deleted. Voiding is reserved for drafts — records that never became ledger truth in the first place.
• Every change is written to an audit log. Actions taken by a connected AI assistant are tagged distinctly, so you always know whether a human or an assistant made a change.

None of this makes the books harder to use day to day. It makes them worth trusting when someone finally asks how a number got there. If you want to see how the pieces fit together, the glossary covers the vocabulary, and you can start a free company and post a correction yourself.