Free Cash Flow Forecast Calculator (Australia) for Tradies & Builders
For Australian trades and construction businesses juggling progress claims, retentions and a wage bill that does not wait for the client to pay.
Last updated 31 May 2026
Cash flow forecasting is harder in trades and construction than almost any other sector, because the money you are owed and the money you owe rarely line up. You pay for materials, plant hire, subbies and wages well before a progress claim is approved and paid, often weeks later under the Security of Payment regime. Retentions hold back a slice of every job until practical completion. A single delayed claim or a head contractor stretching terms to 45 days can turn a profitable project into a cash crisis. This calculator gives you a fast read on where your balance is heading: your forecast ending balance, net monthly cash flow and the lowest point you hit across the period. For builders, electricians, plumbers and earthmoving operators, that lowest-balance figure is the difference between paying your crew on Thursday and scrambling for an overdraft.
How to use this tool
- 1
Enter your opening cash balance
Use the actual cash sitting in your business transaction account today, not your accounting profit. Exclude money quarantined for GST or super if you keep it in a separate account, so the forecast reflects spendable cash.
- 2
Add your average monthly inflow and outflow
Inflow is the cash you genuinely expect to land each month, allowing for 30 to 60 day payment terms. Outflow covers wages, super at 11.5%, rent, stock, loan repayments and your quarterly BAS averaged across the months.
- 3
Set the forecast period and read the three results
Choose 3, 6 or 12 months. The calculator returns your forecast ending balance, net monthly cash flow and the lowest balance in the period, so you can see exactly when cash gets tight before it happens.
Why cash flow, not profit, decides whether you survive
Plenty of profitable Australian businesses fail because they run out of cash, not customers. Profit is an accounting figure. Cash flow is what actually sits in your account when wages, the quarterly BAS, super and supplier invoices all fall due. A cash flow forecast bridges the two by mapping the timing of money in and money out, month by month. The gap usually comes from timing. You invoice a client today but, on 30-day terms, the cash lands five or six weeks later. Meanwhile you have already paid for the materials, the labour and the GST on that sale. A forecast makes those mismatches visible. The three outputs here give you a fast read: the ending balance shows where you finish, net monthly cash flow shows whether you are building or burning cash each month, and the lowest balance flags the tightest point in the period. If that lowest figure dips near zero or below, you have a funding gap to plan for, whether that means chasing debtors harder, negotiating supplier terms, drawing on an overdraft or delaying a discretionary purchase. Run the forecast at the start of each month and compare it against what actually happened. Over time you will calibrate your inflow assumptions to reality, which is where most owners go wrong: they forecast the invoices they sent, not the cash that genuinely arrives once late payers and disputes are factored in. A conservative forecast you trust beats an optimistic one you ignore.
Building realistic AU inflow and outflow assumptions
The forecast is only as good as the two averages you feed it. For inflow, start with your invoiced revenue, then discount for reality. If clients typically pay in 35 days and a handful stretch to 60, the cash hitting your account this month largely reflects sales from one to two months ago. Build that lag into your opening months rather than assuming today's sales convert to today's cash. For outflow, list every recurring payment and convert it to a monthly figure. Wages and PAYG withholding are the big ones, followed by superannuation, now 11.5% of ordinary time earnings and due quarterly by the 28th of October, January, April and July. Many owners forget to set super aside monthly, then face a lump sum that craters the balance. Do the same with your BAS: if you pay GST quarterly, take your typical quarterly liability and divide by three so the monthly outflow reflects the true drag. Add rent, insurance, software subscriptions, loan and equipment finance repayments, fuel and stock. Keep GST in mind throughout. The cash you collect includes the 10% GST you owe the ATO, so do not treat it as yours. If you can, separate it from spendable cash in your opening balance. The more honestly you capture timing and obligations, the more the lowest-balance figure will warn you before a crunch rather than after.
Reading the lowest balance: your early-warning number
Of the three outputs, the lowest balance in the period is the one to watch closest. The ending balance can look healthy while the path to get there dips dangerously low in a particular month, often the month a quarterly BAS or super run lands on top of normal wages. That trough is where businesses get caught short, dishonour a direct debit or pay a supplier late and damage a relationship. Treat the lowest balance as the buffer test. A common rule of thumb is to hold at least one to two months of operating outflow as a cash reserve. If your forecast trough falls below that, you have options worth modelling before the month arrives. You can accelerate inflow by tightening payment terms, invoicing faster, taking deposits or offering a small early-payment incentive. You can smooth outflow by moving annual insurance to monthly, negotiating supplier terms from 30 to 45 days, or timing a large purchase for a stronger month. You can arrange a facility in advance: a business overdraft or invoice finance line is far cheaper to set up when you are not desperate. The point of forecasting is to convert a future surprise into a present decision. Run the numbers, find the trough, and act on it while you still have room to move rather than reacting once the account is already empty.
From manual forecast to a live view of your cash
This calculator gives you a quick, honest snapshot, and for many owners a monthly run is enough to stay ahead. But there is a ceiling to what averages can tell you. A single average inflow hides the lumpy reality of a big project invoice in March and a quiet July. Re-keying figures from your accounting software, your bank feed and your project pipeline into a spreadsheet every month is slow, and by the time you have done it the picture has already moved. The next step up is a forecast that updates itself. When your bank feed, accounting platform such as Xero or MYOB, and your invoicing or job-management system are connected, your cash position can refresh daily without you touching a spreadsheet, with alerts when the projected balance is heading below your buffer. That is the kind of workflow Clever Ops builds for Australian mid-market businesses: pulling live data from the tools you already use into a single, accurate cash view, so you stop forecasting from memory and start managing from real-time numbers. If you find yourself rebuilding this calculation by hand every month, that recurring manual task is usually a sign there is a faster, automatable system waiting to be set up.
Forecasting cash flow on the tools: progress claims, retentions and subbies
Trades cash flow lives and dies on timing. Under Security of Payment legislation in your state, a progress claim follows a payment schedule and a payment date, but in practice many head contractors pay on the last possible day, and disputed claims can stall entirely. Build that lag into your inflow: the cash arriving this month reflects work and claims from one to two months ago, not the job you started yesterday. Then there are retentions, typically 5% held until practical completion and sometimes a further sum through the defects period. That is money you have earned but cannot spend, so do not count it in spendable inflow until it is actually released. On the outflow side, materials and plant hire are paid up front or on tight supplier terms, while your own labour, subcontractors and superannuation at 11.5% are non-negotiable each cycle. Model your quarterly BAS too: GST on a big progress payment can be a serious monthly drag once averaged out. The classic trap is winning a large fixed-price job and funding the early stages, materials, formwork, first-fix, entirely out of pocket before the first claim is paid. Run the forecast across the life of the job and watch the lowest balance. If it goes negative in the early months, you need a deposit, faster claims or a finance facility lined up before you start, not after the account is empty.
Worked example
A Melbourne marketing agency wants to know where its cash will land over the next six months given steady client retainers and a wages-heavy cost base.
- Opening cash balance
- $45,000
- Average monthly inflow
- $82,000
- Average monthly outflow
- $88,000
- Forecast period
- 6 months
Net monthly cash flow: -$6,000. Forecast ending balance: $9,000. Lowest balance in period: $9,000 (month 6).
Outflow exceeds inflow by $6,000 a month, so the agency burns $36,000 over six months and finishes on just $9,000. The trajectory is the warning: at this rate the account runs dry in month eight. The owner has time to lift retainer pricing, tighten payment terms or trim a recurring cost before the buffer disappears.
Who uses this tool
Builder running a fixed-price renovation
A builder takes on a $220k renovation paid in five progress claims. Modelling materials and labour against claim timing, the forecast shows the lowest balance turns negative in month two before the second claim clears, so they negotiate a larger deposit upfront.
Electrical contractor with subbies on the books
An electrical contractor pays subcontractors and apprentices weekly but invoices builders on 45-day terms. The 6-month forecast flags a sharp trough the month BAS and super coincide, prompting them to chase two slow head contractors early.
Earthmoving operator financing plant
An earthmoving operator weighs a new excavator on finance. By adding the monthly repayment to outflow, the forecast confirms net monthly cash flow stays positive in busy months but tips negative over the wet season, so they delay the purchase.
Frequently asked questions
What is a cash flow forecast?
A cash flow forecast is a month-by-month projection of the cash moving in and out of your business and where your bank balance lands as a result. It starts with your opening balance, adds expected inflows and subtracts expected outflows. Unlike a profit figure, it focuses on timing, showing when cash will be tight, which is what actually determines whether you can pay wages, super and your BAS on time.
How is cash flow different from profit?
Profit is an accounting measure of revenue minus expenses over a period. Cash flow is the actual money entering and leaving your account, and when. You can be profitable on paper yet run out of cash because customers pay on 30 or 60 day terms while wages, GST and super are due now. A forecast captures that timing gap, which profit reports simply do not show.
What is net monthly cash flow?
Net monthly cash flow is your average monthly inflow minus your average monthly outflow. A positive figure means you are building cash each month, a negative figure means you are burning it. It is the single best indicator of trajectory: even a healthy opening balance will erode if net monthly cash flow is consistently negative, so it tells you whether the underlying business is funding itself.
Should I include GST and super in my figures?
Yes. The cash you collect includes the 10% GST you owe the ATO, so treat your BAS as an outflow rather than spendable cash, averaging the quarterly liability across the months. Include superannuation at 11.5% of ordinary time earnings, paid quarterly by the 28th of October, January, April and July. Setting both aside monthly stops a quarterly lump sum from blindsiding your balance.
How often should I update my forecast?
Run it at least monthly, ideally at the start of each month, then compare it against what actually happened. This calibrates your inflow assumptions to reality, since most owners overestimate how quickly invoices convert to cash. Businesses with tight margins or lumpy revenue benefit from a fortnightly or even weekly view. The more volatile your cash, the more frequently the forecast earns its keep.
What does the lowest balance figure tell me?
It is the tightest point your bank balance reaches across the forecast period, and your most important early warning. Your ending balance can look healthy while the path dips dangerously low in a single month, often when a quarterly BAS or super run lands on top of normal wages. If the lowest balance falls below your operating buffer, you have time to chase debtors, arrange finance or delay a purchase before the crunch.