Flux analysis works best when the agent explains movements from the postings that caused them, not from guesses about the business. It compares each trial balance line with the prior period and budget, flags movements above your thresholds, traces each to its transactions and drafts an explanation citing them. Account owners confirm the reason; the controller signs the review.
What is flux analysis, and who owns it?
Flux analysis, or fluctuation analysis, compares account balances between periods to find movements that need explaining. It is a close control: unexplained movements are where errors and misstatements show up. Auditors run their own version as an analytical procedure and expect yours to exist.
The input is the trial balance: every account's balance at period end. The financial controller sets the thresholds: an amount, a relative change, or both, often different for balance sheet and income statement lines. Account owners explain movements in their areas. The controller reviews explanations and challenges weak ones.
It overlaps with variance analysis, which compares actuals with budget or forecast for management. Flux analysis is the accounting control; variance analysis is the performance conversation. The agent can serve both, but the evidence each needs is different. The bounds for finance agents generally are in AI agents for finance.
What are the steps, and at what depth?
- Agent, depth 1: pulls the trial balance. Current period, prior period, the same period a year earlier, and budget where useful.
- Agent, depth 1: computes movements and applies thresholds. Every line, with the threshold version applied.
- Agent, depth 1: traces each flagged movement. Pulls the postings that make up the movement, grouped by source: subledger, journal, accrual, reversal, revaluation.
- Agent, depth 2: drafts the explanation. States what moved and which transactions caused it, with references. Where the reason is visible in the data, such as a new contract or a one-off journal, it says so. Where it is not, it asks the owner a specific question.
- Person, account owner: confirms or corrects. Adds the business reason the data cannot show.
- Agent, depth 1: checks consistency. Movements that should mirror each other, such as an accrual on the balance sheet and its expense, are compared. Explanations that contradict each other across accounts are flagged.
- Person, controller: reviews and signs. Challenges explanations, sends weak ones back and signs the analysis.
| Step | The agent does | Depth | Stays with a person |
|---|---|---|---|
| Pull | Trial balance and comparatives | 1 | Nothing |
| Threshold | Flags movements | 1 | Setting thresholds |
| Trace | Finds driving transactions | 1 | Nothing |
| Draft | Explanation with references | 2 | Owner confirms reason |
| Consistency | Cross-checks accounts | 1 | Resolving conflicts |
| Sign | Nothing | none | Controller |
Which controls matter, and what evidence does each leave?
Explanations cite transactions. An explanation without references is refused by the agent's own bounds. Evidence: posting references in each explanation.
Why, not what. "Utilities increased by 40,000 due to higher utilities costs" restates the number. Acceptable explanations name the cause: a new site, a tariff change, a missed accrual last month. Evidence: the owner's confirmation on each line.
Threshold version. Evidence: the threshold set used, approved by the controller.
Balance sheet links. Where a balance sheet movement is flagged, the agent links to that account's reconciliation, prepared as in balance sheet reconciliations with an AI agent. A movement on an account whose reconciliation shows unexplained items gets a second look. Evidence: the link and the reconciliation status.
Controller sign-off. Evidence: signature and date on the analysis.
What evidence does each step leave?
Each flagged line carries a short trail: the movement, the threshold that flagged it, the postings behind it, the agent's draft, the owner's change and the controller's sign-off. Reviewers and auditors can follow any line from number to cause without asking anyone.
For example, an illustrative professional services firm's legal fees line rises from 30,000 to 95,000. The agent traces the movement to two invoices from an outside law firm and an accrual of 40,000 posted by the payables team, and drafts: "Increase of 65,000 driven by two invoices totalling 25,000 and an accrual of 40,000 (journal reference attached). Owner to confirm the matter and whether the accrual is a one-off." The owner adds that the costs relate to a lease dispute expected to end next quarter.
That trail is also how you find weaknesses in the agent. If owners repeatedly rewrite drafts for one account, the agent is reading that account's postings poorly, or the postings themselves are badly described.
What should you measure?
- Drafts confirmed unchanged by owners, by account.
- Explanations sent back by the controller.
- Movements later found to be errors. The control's real output.
- Lines below threshold that turned out to matter, a sign thresholds are wrong.
Where does it usually go wrong?
Plausible but wrong reasons. The agent sees higher sales and says marketing spend rose because of a campaign. The postings show a misallocated invoice. Requiring transaction references stops the agent explaining from general knowledge.
Offsetting movements hidden. An account moves little in total because two large items cancel out. Flux on the net misses both. For high-risk accounts, review gross debits and credits as well as the net.
Thresholds frozen. The business doubles in size and thresholds stay put, flagging everything. Or it shrinks and nothing is flagged. Review them annually.
Explanations copied forward. Last month's text reappears with new numbers. The agent should mark any explanation identical to the prior period's for the owner's attention.
Owners preparing reconciliations can use the same evidence; the balance sheet reconciliation template has a field for flux links.
Questions people ask
Should the agent run flux on every account?
Yes. It costs little, and accounts below threshold can still be listed for a quick scan by owners.
Can auditors rely on our flux analysis?
They decide what to rely on. A clear trail from movement to transaction to confirmed reason makes reliance easier to justify.
What comparatives work best?
Prior month for the close, the same month a year earlier for seasonal businesses, and budget for the income statement. The controller picks per line.