AR Aging Review

By Nupur Mittal

Co-founder at OCTA — works with accounting firms on month-end close and reconciliation automation.

An AR aging review is the process of sorting every outstanding customer invoice by how long it's been unpaid, then using that picture to calculate Days Sales Outstanding (DSO), prioritize collections, and decide how much of the balance is genuinely collectible. It turns a flat list of open invoices into a ranked, actionable view of credit risk. This page walks through the full process step by step, the aging-bucket and DSO math with a worked example, the red flags a careful reviewer watches for, and how accounting firms run this review faster with OCTA Flow while a human approves every provision and write-off.

Why AR aging review matters, and where it goes wrong

Accounts receivable is often the largest asset on a company's balance sheet that isn't cash — and unlike cash, it's a promise, not a fact. A customer who owes $50,000 and pays on time in 30 days is worth something very different from a customer who owes $50,000 and hasn't answered a collection call in four months. An AR aging review is what tells the two apart. It takes every open invoice, ages it against the period-end date, and forces a decision on each one: current and healthy, slow and watched, or at real risk of never being collected.

For a firm or an in-house team, the pain is that this review has to happen every period, across every customer, and it has to combine several different data sources to be useful — the aging report alone doesn't tell you whether a customer has a promise to pay on file, whether they're already over their credit limit, or whether a payment came in last week and just hasn't been applied yet. Done well, the review catches slow-paying customers before they become bad debt, keeps the reserve for doubtful accounts honest, and gives collections a prioritized list instead of a spreadsheet to eyeball. Done poorly — or skipped — it lets receivables quietly age past the point of collectibility while the balance sheet still shows them at full value.

The AR aging review process, step by step

A proper AR aging review follows a consistent sequence. The steps below are the full procedure OCTA Flow executes; they also stand alone as a best-practice process any firm or finance team can follow.

1. Establish the aging buckets. Using the period-end date, calculate days outstanding for every open invoice from its invoice date. Standard buckets: Current (0–30 days), 31–60 days, 61–90 days, 91–120 days, and Over 120 days.

2. Analyze aging by customer. For each customer, total the outstanding balance, split it across the buckets, compare it to the customer's approved credit limit (flag if exceeded), and compare payment history to agreed terms to flag chronic late payers.

3. Calculate DSO. Where sales history is available, calculate Days Sales Outstanding as (Total AR ÷ Total Credit Sales) × Number of Days, both by customer and overall. Compare the result to the prior period and to an industry benchmark — typically 30–45 days for B2B. Flag individual customers with a DSO above 60 days.

4. Review collection activity. Cross-reference the aging report against the collection log. Flag invoices over 60 days outstanding with no collection activity in the last 30 days, review promises to pay for any that were broken, identify disputed invoices and confirm their resolution status, and flag anything already escalated to a collections agency or legal.

5. Identify high-risk balances. Flag customers where a balance is over 90 days with no payment arrangement in place, over 120 days (a high bad-debt-risk threshold), showing a pattern of partial payments, over the credit limit with no approved extension, or tied to a customer known to be in bankruptcy or insolvency.

6. Reconcile unapplied cash. Where cash receipts data is available, identify payments that have been received but not yet applied to an invoice. Flag anything unapplied for more than 7 days and propose applying it to the customer's oldest outstanding invoice first.

7. Reconcile unapplied credit notes. Where credit-note data is available, identify credits that have been issued but not yet applied, flag any unapplied for more than 30 days, and recalculate the customer's net balance once outstanding credits are applied.

8. Assess the bad debt provision. For every balance over 90 days, apply standard provision rates — 91–120 days at 25%, 121–180 days at 50%, and over 180 days at 100% — to calculate a recommended reserve by customer. Compare that recommended reserve to the existing allowance for doubtful accounts and flag any shortfall for an adjusting entry.

9. Check customer concentration risk. Rank the top 10 customers by outstanding balance. Flag any single customer representing more than 15% of total AR, and flag any customer whose outstanding balance exceeds three times their average monthly sales.

10. Summarize AR health. Roll everything up into total AR outstanding, collectible AR (current plus confirmed paying), at-risk AR (61–90 days with limited collection activity), high-risk AR (over 90 days with poor collection response), and an estimated net realizable value after the recommended provisions.

AR aging and DSO (worked example)

Here's how the aging buckets, DSO, and the bad-debt provision tiers come together for a period-end review.

Aging summary — total AR outstanding by bucket:

DSO calculation:

DSO = (Total AR ÷ Total Credit Sales) × Number of Days

With trailing twelve-month credit sales of $2,400,000 and a 365-day period:

DSO = ($370,000 ÷ $2,400,000) × 365 = 56.3 days

Prior period DSO was 51.2 days against an industry benchmark of 30–45 days for B2B — DSO is trending up and already sits above benchmark, which is itself a finding worth escalating even before any single customer breaches the 60-day flag.

Bad debt provision — one customer's assessment:

Assume Redwood Freight Co. is past due across three of the risk tiers:

Redwood Freight Co. currently carries an existing allowance of $6,000 against this balance — a shortfall of $6,450. That shortfall becomes a proposed adjusting entry: Dr Bad Debt Expense $6,450 / Cr Allowance for Doubtful Accounts $6,450, for a reviewer to confirm before it's posted.

Key controls and red flags

The difference between an aging report and a genuine credit-risk review is what you check for beyond the totals. A careful reviewer flags:

• Invoices over 90 days with no collection activity in the last 30 days — a stalled account nobody is chasing
• Customer balances exceeding their approved credit limit — with no documented, approved extension
• Unapplied cash sitting more than 7 days — money already received that isn't reducing the aging it should
• DSO above 60 days for an individual customer, or an overall DSO trending above the 30–45 day B2B benchmark
• Broken promises to pay — a collection commitment that came and went with no payment
• Disputed invoices with no resolution plan or timeline
• A single customer representing more than 15% of total AR — concentration risk that can swing the whole receivable base
• A bad debt reserve that's insufficient for balances over 90 days, based on the standard provision tiers
• Invoices over 180 days with no write-off or legal action — a balance that should have been resolved one way or another
• Credit notes issued but not applied within 30 days — a customer balance that's overstated on paper

Catching these consistently, every customer and every period, is what turns an aging report from a list into a real early-warning system for bad debt.

What a completed AR aging review produces

A finished review isn't just a sorted spreadsheet — it's a documented workpaper a CFO can act on and an auditor can follow. A complete AR aging review package includes:

How OCTA Flow automates AR aging review

OCTA Flow does the aging, the DSO math, and the cross-referencing for you, and leaves the credit decisions and the sign-off with your team. The workflow mirrors the process above:

1. Pick the AR Aging Review Skill. Flow already knows the full procedure: aging buckets, DSO calculation, collection-activity cross-referencing, bad-debt provisioning by tier, and concentration-risk checks.
2. Connect your data. Point Flow at the accounting system, or upload the period's files — the AR aging report, the customer master, and the collection notes log, plus sales history, cash receipts, and credit notes where available.
3. Run. Flow ages every open invoice, calculates DSO by customer and overall, cross-references collection activity, flags high-risk balances and unapplied cash or credits, and computes the recommended bad-debt reserve by customer.
4. Review findings by severity. Instead of a full customer-by-customer aging list, Flow surfaces the exceptions that actually need a decision — ranked by severity, each with a plain-English explanation and a recommended action: email the customer, apply an unapplied receipt, post the bad-debt reserve, escalate a broken promise to the AR manager, or route a credit-limit extension to the CFO for approval. Your team works the exceptions, not every line.
5. Sign off. Once the findings are actioned and any reserve entry is approved, Flow assembles the AR aging review workpaper with the full audit trail intact.

The result: the aging, the DSO math, and the cross-referencing that used to take hours happen in minutes, and your people spend their time on the handful of customers who actually need a judgment call.

Control and trust: Flow proposes, you approve

This is what matters most to a firm or finance team making a credit-risk call with real money attached: OCTA Flow never writes to your books on its own. Every bad-debt reserve entry, every proposed credit application, and every write-off recommendation is a proposal that a human reviews and confirms before anything is posted. Flow does the aging and the math and shows its reasoning; a person makes the call.

That control model runs through the whole review:

• Findings, not silent changes. Flow raises what it found and what it recommends — you decide whether to reserve, escalate, or hold.
• Severity and escalation built in. A customer over 120 days with no payment arrangement is flagged critical and can be escalated to an AR manager or CFO rather than quietly carried forward.
• A complete audit trail. Every aging calculation, proposed reserve, approval, and override is logged, so the review is fully traceable end to end.

You get the speed of automation with the accountability of human sign-off — exactly what a judgment-heavy account like receivables requires.

What the AR aging review draws on

To run an AR aging review, Flow uses the same sources a preparer already works from:

• AR aging report — outstanding invoices by customer and age bucket (required)
• Customer master — credit limits, payment terms, and contact details (required)
• Collection notes — the activity log of calls made, promises to pay, and disputes (required)
• Sales history — the last 12 months of sales by customer, for DSO and trend analysis (optional)
• Cash receipts — recent receipts, to identify payments not yet applied to an invoice (optional)
• Credit notes issued — to identify credits outstanding against a customer balance (optional)

Flow works from whatever your client has connected — it matches each input by its purpose, so it doesn't matter what the files are named or which accounting system they came from.

Related skills and terms

Frequently Asked Questions

What is an accounts receivable aging report? It's a report that sorts every outstanding customer invoice by how long it's been unpaid, typically into buckets like Current (0–30 days), 31–60 days, 61–90 days, 91–120 days, and Over 120 days. It's the starting point for a full AR aging review, which adds DSO, collection activity, and bad-debt provisioning on top.

How do you calculate DSO? Days Sales Outstanding = (Total AR ÷ Total Credit Sales) × Number of Days. It's typically calculated both by customer and overall, then compared to the prior period and to an industry benchmark — commonly 30–45 days for B2B. A rising DSO usually means collections are slowing down relative to sales.

How is a bad debt provision calculated? Standard practice applies a provision rate by aging tier to balances over 90 days — for example 25% for 91–120 days, 50% for 121–180 days, and 100% for anything over 180 days — then compares the resulting recommended reserve to the existing allowance for doubtful accounts. Any shortfall becomes an adjusting entry: debit Bad Debt Expense, credit Allowance for Doubtful Accounts.

What's the difference between an AR aging review and a customer reconciliation? An AR aging review looks across the whole receivables book to assess collectibility, DSO, and bad-debt risk. A customer reconciliation ties one customer's balance in your books to their own records — a statement or their AP ledger — to confirm the two agree line by line. Firms typically run aging reviews on a cadence and customer reconciliations for specific accounts or disputes.

How often should an AR aging review be done? At least monthly, as part of the close, so slow-paying customers and reserve shortfalls surface before they compound. Higher-risk portfolios or customers already flagged are often reviewed weekly.

What is customer concentration risk in AR? It's the risk that a large share of total receivables sits with one customer — commonly flagged when a single customer exceeds 15% of total AR. If that customer's payment slips, it moves the whole receivables picture, so it's tracked separately from ordinary aging.

Can AR aging review be automated? The aging calculation, DSO math, collection cross-referencing, and provision computation can all be automated and then reviewed, while decisions on reserves, write-offs, and credit terms stay with your team. That's the model OCTA Flow uses.

Does OCTA Flow post entries directly to my accounting system? No. Flow proposes every bad-debt reserve entry, payment application, and credit application; a person on your team reviews and approves before anything is posted to the books. Nothing is written automatically.

See how firms turn a raw aging report into a prioritized, fully-documented collections and provisioning review with human sign-off → start a 30-day OCTA Flow trial.