Flux Analysis in Accounting: Definition, Formula & Examples

Your company's revenue increased by 14% last quarter. At first glance, that's great news, but how much of that growth came from new customers? Was there a pricing change? Or did someone accidentally recognize the same revenue twice?

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You can't tell from the financial statements alone, and that's where flux analysis comes in. By comparing financial results across reporting periods, accountants can identify unusual changes, investigate their causes, and catch potential errors before the books are closed.

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A good flux review starts with comparing the numbers, but there's more to it than calculating differences. You also need to know which movements matter, how to investigate them, and what makes an explanation reliable.

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And that starts with understanding what flux analysis actually involves.

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[tldr]

What is flux analysis?

Flux analysis, also known as fluctuation analysis, is an accounting process that compares financial account balances or activity between two reporting periods to identify and explain significant changes.

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Take payroll expenses, for instance. If a company spent $200,000 in May and $250,000 in June, the accounting team has a $50,000 difference to explain. The increase might be reasonable, especially if the company recently expanded its workforce or paid bonuses. 

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But until someone examines the underlying activity, there's no way to know whether the change reflects genuine business activity or an accounting error.

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The goal is to establish what actually caused the change and whether the accounting treatment is correct.

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Finance teams typically perform flux analysis during the month-end close process, although it's also useful for quarterly reporting, financial reviews, and audit preparation.

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The process generally covers two financial statements:

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• Income statement: Revenue, cost of goods sold, payroll, and operating expenses. These accounts help explain how financial performance changed between periods.
• Balance sheet: Cash, accounts receivable, inventory, accrued liabilities, and deferred revenue. Reviewing these balances helps identify unusual changes in assets and liabilities.

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Flux analysis is useful for catching errors that routine reconciliations might overlook. An account can reconcile correctly to its supporting records and still contain a transaction that was posted to the wrong period or classified incorrectly.

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And gaps in these reviews can have consequences beyond the close itself. In KPMG's 2025 study of material weaknesses, 238 companies (7%) disclosed material weaknesses across the 3,307 annual reports in its FY'25 dataset, which covered fiscal year-ends through June 30, 2025 ^[1]. Financial close and reporting was one of the process areas where those weaknesses increased, and the issue KPMG cited most often there was a lack of precision, timeliness, and oversight in management review controls.

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The findings highlight the importance of effective financial reporting controls, including reviews that can identify unexplained movements and potential misstatements before reporting is finalized.

Flux analysis vs. variance analysis

Flux analysis and variance analysis are closely related, and the terms are sometimes used interchangeably. However, they generally compare financial results against different reference points.

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Flux analysis focuses on changes between actual reporting periods. Variance analysis typically compares actual financial results against a budget, forecast, or other expected amount. Auditors draw the same line: PCAOB AS 2305 lists both prior-period financial information and budgets or forecasts as sources for the expectations auditors compare recorded amounts against ^[2].

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Here's how they differ:

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Let's put the difference into perspective with a simple example.

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A company records $500,000 in revenue in June, up from $450,000 in May. With flux analysis, the accounting team would investigate the $50,000 increase to understand what drove the growth.

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But suppose the company had actually budgeted $550,000 in revenue for June. That's where variance analysis comes in. Despite growing revenue by $50,000, the company still missed its revenue target by the same amount.

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Both analyses provide useful insights, but from different angles. Flux analysis explains what changed between reporting periods, while variance analysis helps the finance team understand how actual results compare with expectations.

How to perform flux analysis

A typical flux analysis follows four main steps, from comparing account balances to investigating unusual movements and documenting the findings. 

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Here's how to approach each step:

1. Gather and compare financial data

Start by collecting the financial data for the reporting periods you want to compare. This typically comes from your general ledger, trial balance, or financial reporting system.

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Make sure you're comparing consistent periods and account definitions. For income statement accounts, compare activity within each period. For balance sheet accounts, compare ending balances as of the respective reporting dates.

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You can perform flux analysis across different time frames:

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• Month over month: Compare one month against the previous month to identify recent changes.
• Quarter over quarter: Review financial movements between consecutive quarters.
• Year over year: Compare the same period across different years to understand longer-term changes and account for seasonal patterns.

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The most appropriate comparison depends on the account and the nature of the business.

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For example, a retail company might compare December revenue with the previous December rather than November because holiday sales can create predictable seasonal fluctuations.

2. Calculate financial fluctuations

Once you have the data, calculate the dollar and percentage changes for each account.

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Flux analysis formula for dollar change: Dollar change = Current-period amount − Prior-period amount

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Flux analysis formula for dollar change: Dollar change = Current-period amount − Prior-period amount

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Flux analysis formula for percentage change: Percentage change = (Dollar change ÷ Prior-period amount) × 100

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Suppose a company's operating expenses were $420,000 in May and $485,000 in June.

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The dollar change would be: $485,000 − $420,000 = $65,000

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The percentage change would be: ($65,000 ÷ $420,000) × 100 = 15.5%

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Operating expenses therefore increased by $65,000, or approximately 15.5%, between May and June.

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For balance sheet accounts, pay attention to how debit and credit balances are presented. A report using signed general ledger balances may need to normalize credit balances before calculating percentage movements so that increases and decreases are interpreted consistently.

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If the prior-period amount is zero, the percentage change is undefined. In that case, use the dollar movement to determine whether the account needs further investigation.

3. Identify significant changes

Not every fluctuation deserves the same level of attention. A $200 increase in office supplies might be perfectly normal, while a $50,000 jump in accrued expenses could raise questions.

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To narrow down what needs reviewing, finance teams set thresholds based on dollar amounts, percentage changes, or a combination of both. Accounts that exceed these limits are flagged for further investigation.

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However, the numbers don't always tell the whole story. An increase in payroll after an acquisition might make perfect sense, but what if payroll barely changes despite the company hiring 30 new employees? That could be just as important to investigate. PCAOB AS 2305 uses the same logic for auditors: comparing aggregate salaries with the number of personnel can expose problems that testing individual transactions wouldn't, and a gap between expected and recorded amounts can point to something that was never recorded ^[2].

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This is why accountants also look at expected business activity when deciding which fluctuations need attention, even if they fall below the usual thresholds.

4. Investigate and explain the differences

Once you've identified the significant fluctuations, the next step is to find out what's behind them. This usually involves reviewing general ledger transactions, checking journal entries and invoices, and consulting the relevant teams when additional context is needed.

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Take a company whose other operating expenses increased by $65,000 in June. After reviewing the underlying transactions, the accounting team discovers that $40,000 came from additional marketing expenses and $25,000 from legal fees related to an acquisition.

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Together, these account for the entire increase, giving the team a clear explanation supported by the underlying financial records.

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The findings should be documented in a flux report, along with the supporting records and any adjustments made. If the investigation uncovers an accounting error, the team should correct it and verify the updated balances before signing off on the review.

How to set thresholds for flux analysis

Flux analysis thresholds establish which account movements require further investigation.

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Without thresholds, accountants could spend hours explaining small fluctuations that have little impact on financial reporting. But thresholds that are too high could allow meaningful errors to go unnoticed.

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There are three common approaches:

1. Dollar-based thresholds

These flag changes that exceed a specific monetary amount. For example, a company might investigate any account movement greater than $25,000.

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This approach is straightforward, but it can overlook large percentage changes in smaller accounts.

2. Percentage-based thresholds

These flag changes that exceed a certain percentage of the prior-period amount. For example, an account might require review if its balance changes by more than 10%.

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The downside is that a relatively insignificant dollar movement can produce a large percentage change when the starting balance is small.

3. Combined thresholds

These use both dollar and percentage limits to identify significant changes. Combined thresholds can be applied using two rules:

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• AND rule: A change must exceed both the dollar and percentage thresholds to be flagged.
• OR rule: A change is flagged when it exceeds either threshold.

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Consider a company using thresholds of $25,000 and 10%.

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Notice how office supplies increased by more than 113%, yet the actual dollar movement was only $1,700. The OR rule flags it because the percentage threshold was exceeded, while the AND rule leaves it out because the dollar change is below $25,000.

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This is why threshold rules should reflect account risk and materiality. A large percentage change doesn't necessarily mean a financially significant error, and a small movement can still deserve attention when it affects a sensitive account. The SEC staff makes the same point in Staff Accounting Bulletin No. 99: qualitative factors can make quantitatively small misstatements material ^[3].

Flux analysis example

Let's see how this works for a SaaS company reviewing its June financial results.

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The accounting team compares June activity and ending balances against May, using a review threshold of $10,000 OR 10%. Any account with an absolute dollar change greater than $10,000 or a percentage change greater than 10% is flagged for investigation.

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Here's what the initial flux report looks like:

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‍The expense accounts are presented separately, without overlapping amounts. Revenue represents monthly activity, while accounts receivable and deferred revenue are month-end balances. For simplicity, the example assumes there are no credit memos, write-offs, or other receivables adjustments.

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Under the company's threshold policy, every account except office rent is flagged for review.

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Most of the movements have reasonable explanations:

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• Revenue increased as the company earned more from new customers and existing subscriptions. 
• Payroll rose following new hires, while additional marketing activity and acquisition-related legal fees explain the increase in other operating expenses. 
• Deferred revenue also grew because advance billings exceeded the revenue recognized from previously deferred balances.

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The balance sheet movements also reconcile with the underlying activity. June invoices totaled $1.74 million, while customer collections amounted to $1.45 million, leaving accounts receivable $290,000 higher. 

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Of the $1.74 million in June invoices, $1.16 million related to revenue recognized during the month, while $580,000 was billed in advance for services to be delivered later. ASC 606 presents an amount billed ahead of delivery as a contract liability as soon as payment is made or due, whichever comes first, so it sits in deferred revenue whether or not the customer has paid yet ^[4].

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The company also recognized $260,000 from previously deferred balances, bringing June's total recognized revenue to $1.42 million. As a result, deferred revenue increased by $320,000.

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However, the software subscriptions account reveals something different. During the review, the accountant discovers that a $12,000 annual software subscription covering June through the following May was recorded entirely as an expense in June.

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Assuming the service is received evenly across the 12 months, only $1,000 should be recognized as June's expense. The remaining $11,000 belongs in prepaid expenses. Under accrual accounting, a prepayment stays on the balance sheet as an asset and moves to the income statement as expense only as the company benefits from it ^[5].

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The accountant prepares a correcting journal entry:

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After the correction, June software subscription expense falls from $24,800 to $13,800.

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Compared with May's $12,500, that's now a $1,300 increase, or 10.4%, rather than the original $12,300 increase.

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The account still exceeds the 10% review threshold, but the remaining movement is explained by the $1,000 June expense from the annual contract and $300 in other net changes. The accountant can document the explanation and complete the review.

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A significant fluctuation doesn't always indicate an accounting error, and correcting an error doesn't necessarily eliminate the fluctuation. The purpose of the review is to ensure that the remaining movement is accurate, supported, and properly explained.

How to write effective flux analysis explanations

A good flux explanation should make it easy for someone reviewing the financial statements to understand what changed, why it changed, and whether the amount is correct.

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The stronger explanations make the review easier because they identify the actual drivers and quantify their contributions.

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When documenting significant fluctuations, follow three practices:

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1. Explain the movement in measurable terms. Identify the major contributing factors and their dollar amounts. Where possible, those amounts should reconcile to the overall change.
2. Include supporting documentation. Reference the invoices, contracts, payroll records, or journal entries used to validate the explanation. This creates a clear trail for internal reviewers and auditors.
3. Require reviewer approval. Once the preparer completes the analysis, a controller or designated reviewer should assess the findings, confirm that any required corrections have been made, and sign off.

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A well-documented flux report can also become a useful reference for future reporting periods, particularly when the same account shows recurring or seasonal fluctuations.

Common flux analysis mistakes

Flux analysis can be a valuable check during close, but its usefulness depends on how thoroughly the review is performed. Even when the calculations are correct, inconsistent data, poorly chosen thresholds, or weak explanations can make it difficult to spot the issues that matter.

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Here are five mistakes worth watching out for:

1. Comparing inconsistent reporting periods

It's easy to draw the wrong conclusions when you're comparing numbers that aren't on the same basis.

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Say you're reviewing June expenses against May, but the June books are still missing several accruals. Some expenses will appear unusually low, even though the difference has more to do with incomplete accounting than actual business activity.

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Before running the analysis, make sure both periods follow the same accounting policies and account classifications. You should also account for any outstanding close adjustments so you're not spending time investigating fluctuations that will disappear once the books are updated.

2. Setting thresholds too high or too low

A threshold of $50,000 might be reasonable for one company and completely wrong for another. Even within the same business, the level of scrutiny needed for a cash account will likely differ from what's required for office supplies.

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Set your thresholds too high, and potentially important movements go unnoticed. Set them too low, and accountants end up explaining dozens of minor changes that have little bearing on the financial statements.

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A better approach is to establish thresholds based on materiality, account risk, and the nature of the business, then revisit them as the company grows. Auditors work from the same yardstick: under AS 2305, the amount of difference an auditor can accept without further investigation is influenced primarily by materiality ^[2].

3. Ignoring accounts that don't exceed the thresholds

Sometimes, the absence of a change is exactly what should catch your attention.

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Imagine an accrued expense account that hasn't moved for three months, even though the underlying obligation should have been settled. A standard threshold check might not flag it because there's no significant fluctuation to investigate.

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That's why a good flux review also considers what should have happened. Unexpectedly static balances, unusual account relationships, and changes that don't align with business activity can all warrant a closer look.

4. Explaining fluctuations without checking the evidence

It's tempting to write something like "payroll increased due to hiring" and move on, especially when you're working through a long list of accounts.

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But unless you've reviewed the payroll register or hiring records, you're making an assumption. And if the increase includes bonus payments or an incorrectly posted expense, that explanation won't hold up under further review. Auditors won't take it at face value either: AS 2810 requires them to obtain corroboration for management's explanations of significant unusual or unexpected amounts ^[6].

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Where possible, tie each significant movement to specific transactions, quantify the contributing factors, and reference the documents that support your conclusion.

5. Leaving identified errors unresolved

Finding an error during flux analysis is only half the job. If the adjustment never gets posted, the incorrect balance still makes its way into the financial statements.

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When an investigation reveals a misclassification, missed accrual, or incorrect posting, prepare the appropriate journal entry and verify that it resolves the issue before completing the review.

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It also helps to connect flux analysis with balance sheet reconciliation and other close activities, so outstanding issues are tracked through to resolution rather than forgotten after the review.

Automate flux analysis with DualEntry

Closing the books still takes longer than many finance teams would like. According to APQC's financial close benchmark, organizations take a median of eight days to complete their monthly financial close, based on data from 3,389 companies ^[7]. A separate APQC measure, running from the initial trial balance to finished consolidated financial statements, puts the median at 6.0 calendar days across 11,223 organizations ^[8].

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As a company grows, flux analysis alone can involve hundreds of account comparisons, each requiring calculations, supporting records, and explanations.

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DualEntry's financial reporting software helps reduce that workload by automating flux analysis directly within the ERP. Rather than rebuilding comparisons in a spreadsheet every month, finance teams can compare financial results, identify significant changes, and investigate their causes using the underlying accounting data.

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Here's how DualEntry supports the process:

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• Automated account comparisons: Review month-over-month movements on the income statement and balance sheet, plus quarter-over-quarter and year-to-date versus prior year-to-date movements on the income statement, without manually rebuilding reports.
• Custom review thresholds: Set a dollar limit, a percentage limit, or both (with AND or OR logic) to automatically flag significant fluctuations, and require an explanation on every flagged account.
• AI-assisted explanations: Generate a draft explanation for a flagged account from its transactions, ranking the vendors or customers that drove the change and calling out large postings, for accountants to accept, edit, or discard.
• Transaction-level drill-downs: Open a flagged account and drill into the journal entries that make up its balance to see what's driving the change.
• Connected close management: Add a flux review task to the close checklist that completes automatically once every flagged account has commentary and the analysis is marked complete, assign each close task to an owner, and export the analysis with its commentary to Excel or PDF through DualEntry's close management software.

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With much of the preparation handled automatically, accountants have more time to focus on the work that requires their judgment, from investigating unusual activity to validating explanations and correcting errors before close.

Flux analysis FAQs