Invoice Finance Calculator

Almost every invoice finance calculator online is run by a lender or a broker, and they all do the same small sum: invoice value, multiplied by a fee rate, multiplied by an advance rate. That tells you roughly what one invoice costs. It doesn't tell you the two things that actually catch businesses out.

The first is timing. Invoice finance pays you twice, not once: an advance now, then the rest of the invoice — the reserve — minus charges, whenever your customer finally pays. Those are two separate cash events, often two or three months apart, and your cash flow forecast is fiction unless it treats them separately.

The second is the recourse clock. Fund an invoice and you have a deadline: if your customer hasn't paid within the recourse period, that invoice drops out of your funding base. Your available funds shrink and nothing bounces, no letter arrives — the number in the lender's portal just goes down. The tracker tab here rebuilds that calculation from your own ledger so you can see it coming.

Most small businesses already run a cash flow forecast in their accounting software, and for a business without a facility it works well. Feed it your sales ledger and it draws a projected bank balance: money in, money out, a line you can read, and a warning when you dip below zero. That format is genuinely the right one — it is the question owners actually ask, which is "will I make payroll?"

The problem is what those forecasters do with a financed invoice. They take the invoice value and put it on the due date, because that is all a sales ledger tells them. For anyone on invoice finance that is wrong twice over. Wrong in amount, because you never receive the invoice value — you receive an advance of 80% to 90% now, then the reserve minus charges later. And wrong in date, because the second payment lands when your customer actually pays, not when the invoice falls due.

On a £60,000 invoice at an 85% advance rate, a due-date forecaster shows £60,000 arriving on day 60. Reality is £51,000 already banked and about £7,900 arriving on day 75 or later. The forecast is overstating that month by roughly £52,000 and understating the previous month by the same. If your customer drifts past the recourse period, the truth is worse still: the advance is clawed back and the line moves the other way.

The forecast tab here keeps the format and fixes the model. Enter your bank balance, add your outgoings, and it splits every financed invoice into its advance and its reserve release, dates the reserve from each debtor's real average payment behaviour, applies a clawback if payment is expected after the recourse date, and pays non-financed invoices in full straight to the bank. Same chart your accountant expects. Numbers you can actually bank on.

The two products are constantly confused, including by people using them. With factoring, you sell the invoice and the lender takes over credit control: your customer is told, and pays the factor directly. It's disclosed, and it suits smaller businesses who'd rather someone else chased.

With invoice discounting you borrow against the ledger instead. You keep credit control and your customer usually has no idea a lender is involved — that's why it's often called confidential invoice discounting. To secure it, the lender requires customer payments to go into a trust account: an account in your company's name, so it looks entirely normal on your invoice, but controlled by and charged to the lender. Money lands there, the lender sweeps it, nets off what you owe, and releases the surplus.

There's a middle option too, CHOCS — Customer Handles Own Collections — where the arrangement is disclosed but you still do the chasing.

The practical consequence: if you're on discounting, chasing late payers is your job, and no one will warn you when an invoice is about to age out of the funding base. That's the gap this tool fills.

UK facilities usually have two charges, which is why comparing them against a single headline percentage is so misleading.

The service fee (or administration fee) is a percentage of the invoice value, typically between 0.5% and 3% depending on turnover, sector and whether the lender is doing your credit control. It's charged on everything that goes through the facility, whether or not you draw the money.

The discount charge is interest on the money you've actually drawn, quoted as a margin over base rate and accruing daily. Two facilities with the same service fee can differ a lot here, especially if your customers are slow, because you pay for every extra day the advance is outstanding.

Then there are the extras that never appear in the headline rate: arrangement or set-up fees, CHAPS and same-day payment charges, audit or survey fees, and refactoring charges on invoices that go past their recourse date. Switch the calculator to the two-part option to model this properly, and put your CHAPS charge in the fixed-charges box — on a small invoice it can matter more than the rate.

A 1.5% fee sounds cheap next to an overdraft at 9.5% a year. They aren't comparable, because the 1.5% buys you about 60 days of money and the 9.5% buys you a year of it.

To compare them, annualise. Take the total charges, divide by the cash you actually received, then scale by 365 divided by the days the money was outstanding. Financing a £50,000 invoice for £1,500 in charges with a £42,500 advance over 60 days is a 3% cost of that invoice — but about 21% a year. That is the figure to hold next to your overdraft rate.

This isn't an argument against invoice finance. It's frequently the right call: it scales with your sales, it doesn't need the security a term loan needs, and being able to pay staff this month is worth real money. But you should know which number you're comparing, and the calculator shows both.

Nearly all UK invoice finance is on a recourse basis. If your customer doesn't pay within the recourse period — commonly 90 days, and very often counted as 90 days from the end of the invoice month rather than from the invoice date — the invoice becomes disapproved. The lender takes it out of the funding calculation, and your availability falls by that invoice's value times your advance rate.

That wording matters. Under a 90-day end-of-month convention, an invoice dated 3 June and one dated 28 June share the same deadline. Businesses that assume they get 90 days from each invoice date lose several weeks they thought they had. Set the convention in the tracker to match your agreement.

So a customer paying three weeks late isn't just annoying. If it pushes the invoice past recourse, a five-figure advance you'd already planned around comes out of the funding base, usually in the same week you needed it for payroll. This is exactly the scenario the deadline board is for: it lists every invoice by how soon it disapproves, and shows the funding at stake, so you know which customer to phone today.

The availability figure in your lender's portal isn't your ledger times the advance rate, which is why it so often reads lower than expected. It's a sequence of deductions, and the order matters:

Start with the outstanding invoices you've assigned to the facility. Take out the disapprovals — anything past the recourse period, in dispute, and depending on your agreement, overseas debtors, related-party invoices, or customers over their credit limit. What's left is your eligible ledger.

Now apply the concentration limit. Most facilities cap how much of the funding base any single customer can represent — 25% to 50% is typical. If your eligible ledger is £100,000 with a 50% cap and one customer owes £60,000, then £10,000 of that customer's debt is excluded. The cap is applied to the ledger after disapprovals, not before, so an aged invoice elsewhere can quietly tighten the cap on your biggest customer.

Multiply what survives by your advance rate for gross availability, cap it at your facility limit, then subtract funds in use — what you've already drawn. That's what you can actually take today. The tracker shows every line of this with the reason attached, which is the part the client statement leaves you to work out yourself.

There's no bank feed and no lender integration here, and that's deliberate — for invoice discounting, a bank feed wouldn't help. Your customers pay into the trust account, not your current account, so your bank statement shows lender sweeps and releases in lump sums that don't correspond to individual invoices. The datasets that answer the real questions are your invoice ledger and one figure off your lender statement.

So: set your facility terms once from your agreement, import your outstanding invoices from a Xero, QuickBooks or Sage CSV export (upload it and pick which column is which), and type in your current funds in use. Mark invoices paid as they settle. That takes a few minutes a week and gives you the availability figure, the recourse deadlines and the forward cash curve.

It also learns. Once you've marked a few invoices paid, the tool works out each customer's real average time to pay and uses that for the forecast instead of your agreed terms — so a customer who reliably pays at day 75 on 60-day terms is forecast at 75. Everything is stored in this browser only; use the backup button to move it to another machine.