Debtor management is the system you use to get invoices out on time, follow up overdue accounts, and fix the reasons clients do not pay. Done properly it turns profit on paper into cash in the bank. Where a debt is genuinely unrecoverable, Australian tax law lets you claim a deduction if you write it off before year end.

Most business owners who come to us with a cash flow problem do not have a profit problem. They have a debtor problem. The work has been done, the margin is there, the profit and loss looks fine, and yet there is nothing in the bank account on the 25th when superannuation and wages are due.

Worse, an unpaid invoice does not sit there quietly. It actively takes money out of your business, because you are taxed on the profit and you remit the GST whether or not the client ever pays. I am Mina Baselyous, a Certified Practising Accountant (CPA) and Chartered Tax Advisor (CTA) in Melbourne, and this article walks through exactly what an unpaid invoice costs you, how to build a debtor system that runs without you chasing it, and how to recover the tax and the GST when a client genuinely will not pay.

What an Unpaid Invoice Actually Costs You

An unpaid invoice is not neutral. If you report on an accruals basis, raising the invoice books the sale, lifts your profit, and creates a tax liability. It also creates a GST liability you pay to the ATO dollar for dollar. So the invoice costs you the work, the materials, the wages, the GST and the income tax, all before a cent arrives.

Most owners have never seen this laid out in numbers, so here it is.

Worked Example: One $110,000 Invoice That Never Gets Paid

A company completes a job in May and invoices the client $110,000 including GST. The job cost $77,000 including GST in materials, subcontractors and wages, all already paid. The company reports GST quarterly on an accruals basis and pays company tax at 25 per cent. The client goes quiet.

• Revenue recognised: the invoice is $110,000 GST inclusive, so $110,000 divided by 11 is $10,000 of GST, and $100,000 is assessable income.
• Costs deducted: $77,000 GST inclusive, so $7,000 of GST credits and $70,000 of deductible cost.
• Taxable profit on the job: $100,000 less $70,000 equals $30,000.
• Company tax at 25 per cent: $7,500, payable through PAYG instalments or at lodgement.
• Net GST on the job: $10,000 collected on the sale less $7,000 credits on the costs equals $3,000 remitted on the next BAS.
• Cash received from the client: nil.

Add it up. The business has already spent $77,000 delivering the job, and it now has to find another $3,000 for the ATO on the BAS and $7,500 in income tax on a profit it has never seen. That is $87,500 of cash out the door against zero cash in. The profit and loss says the business made $30,000. The bank account says it is $87,500 down.

This is the mechanism behind almost every “profitable but broke” conversation we have. If you want the full picture of how profit and cash diverge across debtors, stock and work in progress, see our guide to working capital and the cash trapped in your business.

The pain is not unique to you. The Australian Small Business and Family Enterprise Ombudsman’s small business data portal records that in 2025-26, payment disputes were the second most common issue small businesses brought to the Ombudsman, with 707 cases, and notes plainly that delayed or unpaid invoices place pressure on cash flow.

Does Your GST Method Change This? Cash vs Accruals

Yes, substantially. On the accruals (non-cash) method you report GST in the period you issue the tax invoice or receive payment, whichever happens first, so you fund the ATO before the client funds you. On the cash method you report GST only when the money actually arrives, so an unpaid invoice creates no GST liability at all.

The ATO’s choosing an accounting method guidance, current as at September 2026, sets out the rule directly: on the non-cash basis you account for the GST payable on your sales in the reporting period in which you issue a tax invoice or receive full or part payment, whichever happens first. Businesses with an aggregated turnover of less than $10 million can choose the cash method.

In the example above, the same job on a cash basis produces no GST liability until the client pays. That is a $3,000 difference in cash on one invoice. Across a year of slow paying customers, it is often the difference between needing an overdraft and not needing one.

It is not a free lunch, because you also cannot claim GST credits on your purchases until you have paid them, and the income tax treatment is a separate question from the GST method. We have set out the full comparison, the eligibility rules and how to switch in our guide to GST on a cash versus accruals basis. If your debtors ledger is consistently large and slow, reviewing your GST method is one of the fastest cash wins available to you.

One caution before you switch: the bad debt deduction and the GST bad debt adjustment discussed later in this article are mostly relevant to accruals taxpayers. If you are on a cash basis you never paid the tax or the GST in the first place, so there is nothing to claim back.

Question One: Are Your Invoices Actually Going Out on Time?

Before you blame the client, check the calendar. If the job finished on the 3rd and the invoice went out on the 28th, your 30 day terms just became 55 day terms and nobody is late but you. Invoicing delay is the single most common and most fixable cause of a blown out debtors ledger, and it costs you nothing to fix.

Work through this honestly:

• How many days pass between the work being completed and the invoice being raised? Measure it for the last twenty jobs.
• Who is responsible for raising the invoice, and is it their job or something they do when they get a chance?
• Are you waiting to batch invoices at month end? That habit alone can add three weeks to your collection cycle.
• Do progress claims go out on schedule, or only when someone remembers?
• Is the invoice correct the first time? A wrong purchase order number or a missing reference can park an invoice in a client’s exceptions queue for a month.

For larger clients, invoicing correctly matters as much as invoicing quickly. If their accounts payable system needs a purchase order number, a cost centre, a signed variation or a timesheet attached, a missing field does not generate a phone call. It generates silence. Ask each major customer once what their accounts payable process requires, then build it into your invoice template.

Invoicing on time also depends on the books being in a fit state to invoice from. If job costing, timesheets and purchase coding are behind, the invoice cannot go out. That is one of the practical reasons we treat bookkeeping as the foundation of every advisory engagement rather than an afterthought.

Question Two: Is Anybody Actually Following Up?

Most small businesses have no reminder system at all. They have a memory, a sense of unease, and an awkward phone call once the debt is three months old. A reminder ladder fixes this: a fixed, scheduled, escalating sequence of contact that happens automatically whether or not the owner is thinking about it that week.

A Follow Up Ladder That Works

• Day 0: invoice issued, emailed to the correct accounts contact, not just the person who engaged you.
• Day minus 3 (before due date): a short, friendly automated reminder that the invoice falls due shortly. This one email prevents more late payments than everything that follows.
• Day 1 overdue: automated reminder, polite, with the invoice attached and payment options repeated.
• Day 7 overdue: a phone call from a real person. Not an email. The purpose is not to demand payment, it is to find out what the problem is.
• Day 14 overdue: written follow up confirming what was discussed on the call and the agreed payment date.
• Day 30 overdue: formal letter from the business owner, work paused if appropriate, payment plan offered if the client is genuinely struggling.
• Day 45 to 60: letter of demand, then referral to a collection agent or your solicitor.

Two things make this work. First, it is automated where it can be, so nothing depends on somebody remembering. Xero, MYOB and most accounting platforms will send scheduled reminders for you. Second, the phone call at day 7 is non negotiable. Email chasing is comfortable and largely useless. A two minute call tells you within thirty seconds which of the four problems below you are actually dealing with.

Keep every reminder, every call note and every letter. It is good practice, and as you will see further down, it is also what the ATO expects to see if you later want to claim the debt as a deduction.

Question Three: Why Is This Client Not Paying?

There are only four real reasons a client has not paid you: they forgot, they were surprised by the price, they are unhappy with what was delivered, or they cannot afford it. Each one has a completely different fix, and chasing all four the same way is why so many follow up systems fail. Diagnose first, then chase.

1. They Forgot

This is the majority of overdue invoices and the easiest to solve. The invoice went to the wrong inbox, it landed while the bookkeeper was on leave, or it simply got buried. The fix is systems, not relationship management: correct accounts contact, automated reminders, clear payment options, and a statement at the start of each month. If most of your debtors fall into this bucket, you do not have a client problem, you have a process gap.

2. They Were Surprised by the Price

The invoice is larger than the client expected, so instead of arguing they simply do not pay it and hope you do not ask. This is almost always a quoting and scope problem, not a collections problem. Variations were done on a handshake, scope crept, or the original quote was vague enough that both sides heard what they wanted to hear.

The fix sits upstream. Quote in writing with inclusions and exclusions spelled out. Price variations before you do them, not after. Where a job is going to run over, tell the client while it is happening rather than at invoice time. In practice, says Mina Baselyous (CPA, CTA, Registered Tax Agent), the businesses with the cleanest debtors ledgers are almost never the toughest at chasing money. They are the clearest at setting expectations before the work starts.

If your pricing itself is the problem rather than the communication, that is a different conversation again, and our article on profit margins is the better starting point.

3. The Work Was Not Delivered the Way They Expected

A withheld payment is often a complaint that nobody escalated. Something was late, something was wrong, someone did not call back, and the client has decided that not paying is the cleanest way to get your attention. It usually works, which is exactly why it keeps happening.

If this is a recurring theme across several debtors, the problem is not your collections process, it is your service delivery. Look at handover, communication during the job, quality control, and whether anyone owns the client relationship after the sale. Fixing that lifts your margins, your referrals and your debtor days all at once. It is the same principle we apply when helping clients read the operational story behind their numbers in a profit and loss statement: the ledger is telling you something about how the business actually runs.

4. They Genuinely Cannot Pay

Some clients are in trouble. The earlier you find this out, the better your position, because the businesses that get paid in a cash squeeze are the ones that asked first. Offer a structured payment plan in writing, secure what you can, stop supplying on credit, and consider whether you need to be registered on the Personal Property Securities Register for goods you have supplied.

This is also the group where credit checks earn their keep. Running a credit check before extending significant terms to a new customer, and setting a credit limit you are comfortable losing, is cheaper than the write off. And if the squeeze is happening in your own business rather than your customer’s, deal with it early: our guides to ATO payment plans and the ATO’s renewed debt collection activity explain what the Commissioner is doing in 2026 and why waiting is the expensive option.

Fix the System, Not Just the Symptom

Chasing debtors harder treats the symptom. The structural fix is to change the terms of trade so less money is at risk in the first place. Deposits, progress claims, shorter terms, direct debit authorities and clear written agreements do more for your cash position than any amount of follow up, because they change the rules rather than the effort.

• Take a deposit. For project work, 30 to 50 per cent up front is normal in most industries. A client who will not pay a deposit is telling you something.
• Bill in stages. Progress claims against milestones keep your exposure small and surface problems early.
• Shorten your terms. Fourteen days is a legitimate commercial term for most small business work. Thirty days is a habit, not a law.
• Make paying easy. Card, direct debit and payment links on the invoice remove friction. The small merchant fee is cheaper than 40 extra debtor days.
• Get it in writing. A signed engagement letter or terms of trade, with interest on overdue amounts and recovery costs specified, is what your solicitor will need if it ever goes that far.
• Set a stop supply rule. Decide in advance at what point work pauses, and apply it consistently. Continuing to supply a client who is 90 days overdue is a decision to lend them money.
• Separate the money. Keeping GST and tax in their own accounts, rather than one operating account, stops you spending money that was never yours. Our article on the six bank accounts every business owner needs sets out the structure we recommend.

Measure It: Debtor Days and the Ageing Report

You cannot manage what you do not measure. Two numbers tell you almost everything: debtor days, which is average debtors divided by annual sales multiplied by 365, and the aged receivables report broken into current, 30, 60 and 90 plus day buckets. Review both monthly, at the same meeting, against a target you have actually set.

If your terms are 30 days and your debtor days are 62, you are funding roughly a month of sales out of your own pocket. On $1.5 million of turnover that is about $130,000 of working capital tied up for no return. Bringing it back to 40 days releases roughly $90,000 in cash without selling anything extra.

Debtor days is one of a small handful of numbers that actually run a business. If you are building a monthly reporting pack from scratch, start with our list of the five financial numbers every small business owner must know.

The 90 plus column is the one to watch. Debts rarely improve with age, and the older bucket is where your eventual write offs are already sitting. If it is growing quarter on quarter, escalate now rather than at year end. This is exactly the kind of number a Virtual CFO engagement puts in front of you every month, alongside your budget and cash flow forecast, so the conversation happens while there is still time to act.

None of this works on bad data. If your bank feeds are not reconciled and payments are not allocated against the right invoices, your ageing report is fiction and you will end up chasing clients who have already paid. Clean books come first, which is why we start every advisory engagement with the ledger and a proper bank reconciliation process.

When the Debt Is Genuinely Bad: Writing It Off for Tax

If you have chased a debt properly and it is not coming, you can claim a tax deduction for it. The ATO requires three things: the amount must have been included in your assessable income, the debt must actually be bad rather than merely doubtful, and you must write it off as bad in writing before the end of the income year in which you claim it.

Those three conditions come straight from the ATO’s guidance on deductions for unrecoverable income (bad debts), current as at September 2026. The detail sits in Taxation Ruling TR 92/18, which remains the Commissioner’s stated view on when a debt is bad and what writing off actually means.

What Makes a Debt Bad Rather Than Just Old

Age alone is not enough. TR 92/18 is explicit that a debt will not be accepted as bad merely because a set period such as 180 or 270 days has passed with no payment. What is required is a bona fide commercial judgement, based on the facts, that there is little or no likelihood of recovery. A debt that is merely doubtful does not qualify.

The ruling accepts a debt as bad where, for example, the debtor has died leaving insufficient assets, cannot be traced, is a company in liquidation or receivership with insufficient funds, the debt has become statute barred, or on an objective view of the facts there is little or no prospect of recovery. You do not have to exhaust every legal avenue, but you do have to make a genuine, evidenced assessment.

Document What You Did to Collect

This is where the follow up ladder pays you back a second time. TR 92/18 lists the steps that support a write off, and the ATO’s own guidance points to evidence such as reminder notices issued and attempts to contact the debtor by phone or mail. The taxpayer carries the onus of proof, so your file needs to show the work, not just the conclusion.

Depending on the size of the debt, a defensible file typically includes some or all of the following:

• Copies of the original invoice and the reminder notices issued.
• A record of telephone and email contact attempts, with dates.
• A reasonable period elapsed since the due date, judged against the size of the debt and your credit arrangements.
• A formal letter of demand where the amount warranted it.
• Any summons issued, judgment obtained, or enforcement action taken.
• Correspondence from a liquidator, administrator or trustee in bankruptcy.
• A file note recording your assessment of why the debt is not recoverable.

The Write Off Must Happen Before Year End

This is the trap that costs business owners the deduction. A provision for doubtful debts is not a write off. The decision to write the debt off as bad must be made and recorded in writing before 30 June, not when the accounts are being prepared in October. TR 92/18 makes clear that a balance day adjustment made after the year has closed is too late.

The good news is that the recording does not need to be elaborate. A board minute, a written recommendation approved by a director, or a dated file note authorising the write off is sufficient, even if the accounting entry is processed afterwards. What is fatal is having nothing in writing before year end. This is precisely why we run a bad debt review with clients in May and June as part of tax planning, rather than discovering the problem at lodgement.

Claim the GST Back as Well

If you account for GST on an accruals basis, you have already paid the ATO the GST on an invoice your client never paid. You can claim a decreasing adjustment to get it back where you made a taxable sale, paid the GST, have not received the consideration, and have either written the debt off as bad or the debt has been overdue for 12 months or more.

The adjustment is claimed in the tax period in which you write off the debt, or in which you become aware that the debt has been overdue for 12 months or more. In our experience it is one of the most commonly missed adjustments on small business BAS returns, which is one of several reasons we argue that your accountant, not your bookkeeper, should lodge your BAS.

Worked Example: The Same $110,000 Invoice, Written Off

Go back to the job from earlier. The client has gone into liquidation and the liquidator has confirmed there will be no distribution to unsecured creditors. The debt is bad. The company records the write off in writing in June, before year end. Here is what comes back.

• Income tax deduction: $100,000, being the GST exclusive amount previously included in assessable income. At 25 per cent that is $25,000 of tax relief, which offsets the $25,000 of tax originally attributable to that revenue.
• GST decreasing adjustment: $10,000, claimed on the BAS for the period in which the debt was written off.
• Net position on the job: the company is out of pocket the $70,000 of GST exclusive costs it actually incurred, and nothing more.

That is the whole point of doing this properly. Handled correctly, a bad debt costs you your costs. Handled badly, by missing the write off deadline or never claiming the GST adjustment, it costs you your costs plus $25,000 of tax plus $10,000 of GST on income you never received. A bad debt you documented is a deduction. A bad debt you ignored is just a loss.

Four Traps to Watch

• Cash basis taxpayers cannot claim. If you return income on a cash receipts basis, the unpaid amount was never included in your assessable income, so there is no deduction available. TR 92/18 is clear on this, and the same logic applies to the GST adjustment.
• Companies face continuity tests. A company claiming a bad debt deduction must satisfy a continuity of ownership test or, failing that, a same business style test between the year the debt arose and the year it is written off. If your shareholding has changed, get advice before claiming.
• Related party debts attract attention. The ATO has flagged the arm’s length treatment of debts within closely held groups as an area it examines, along with the genuine nature of the bad debt and the supporting documentation. Writing off a loan to a related entity is not the same as writing off a customer invoice, and if the debtor is your own company you are also in Division 7A territory.
• Recoveries are assessable. If the client later pays, the recovered amount goes back into your assessable income in the year you receive it. Writing a debt off does not release the debtor from the liability, so keep the file open.

Where to Start This Month

Pick the three actions that move the most cash: measure the gap between job completion and invoice date, turn on automated reminders including one before the due date, and pull your aged receivables report to identify everything past 90 days. Those three steps alone typically release a meaningful amount of working capital within a quarter.

Then deal with the old debt properly. Work through the 90 plus column, decide which debts are genuinely recoverable, escalate those, and build the file on the ones that are not so the write off is defensible before 30 June. At the same time, ask whether your GST accounting method still suits the way your customers actually pay you.

This is the sort of work that sits between compliance and strategy, which is where most accountants never go. If your accountant only speaks to you after year end, you may find it useful to read our take on the signs you have outgrown your accountant.

Frequently Asked Questions

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