Borrowing Base Calculator
The cash an invoice finance facility actually makes available is not the advance rate multiplied by your sales ledger. A funder first strips out the parts of the ledger it will not fund: invoices past its age limit, the portion of your largest customer above its concentration cap, contra balances where the customer is also a supplier, and any reserve it holds. Only what survives, the eligible debt, gets the advance rate applied. This tool shows each deduction separately so you can see where the gap comes from.
Your ledger
Default 90%: the most common published headline advance rate across the 27 providers we hold full structured terms for. Change it to your own funder's rate.
Where the ledger goes
| Total sales ledger | £500,000 |
| less aged debt | -£40,000 |
| less concentration excess | -£25,000 |
| less contra balances | -£10,000 |
| less other reserves | -£0 |
| Eligible debt | £425,000 |
| Indicative availability | £382,500 |
Arithmetic on the figures you entered, not a quote, an offer or a decision. Age limits, concentration caps, contra treatment and reserves are set by each funder and differ between them, which is why the same ledger produces different availability at different providers.
| Line | Amount | What it is |
|---|---|---|
| Total sales ledger | £500,000 | Everything currently invoiced and outstanding |
| Less aged debt | -£40,000 | Invoices past the funder's age limit, commonly 90 or 120 days |
| Less concentration excess | -£25,000 | The largest customer's £150,000 against a 25% cap on a £500,000 ledger |
| Less contra balances | -£10,000 | Where the customer is also a supplier and can set off |
| Less other reserves | -£0 | Disputed items, credit notes and funder-specific reserves |
| Eligible debt | £425,000 | The part of the ledger the funder will actually advance against |
| Indicative availability | £382,500 | Eligible debt at a 90% advance rate |
Source: Market Invoice borrowing base model; advance-rate default derived from the structured provider terms in providers.ts
Illustrative. Every deduction is a funder policy, not a market constant.
View as plain-text Markdown
### Worked example: the default scenario above | Line | Amount | What it is | | --- | --- | --- | | Total sales ledger | £500,000 | Everything currently invoiced and outstanding | | Less aged debt | -£40,000 | Invoices past the funder's age limit, commonly 90 or 120 days | | Less concentration excess | -£25,000 | The largest customer's £150,000 against a 25% cap on a £500,000 ledger | | Less contra balances | -£10,000 | Where the customer is also a supplier and can set off | | Less other reserves | -£0 | Disputed items, credit notes and funder-specific reserves | | Eligible debt | £425,000 | The part of the ledger the funder will actually advance against | | Indicative availability | £382,500 | Eligible debt at a 90% advance rate | Source: Market Invoice borrowing base model; advance-rate default derived from the structured provider terms in providers.ts Illustrative. Every deduction is a funder policy, not a market constant.
“The deductions here are the ones you can see. The ones that catch people out are structural: contractual or stage-payment billing that a funder treats as not yet due, a ban-on-assignment clause in a customer contract that makes an otherwise perfect debt unfundable, and dilution from credit notes that shows up as a reserve only after the first few months of trading history. A ledger can pass this calculation comfortably and still fund short, so treat the output as the shape of the answer rather than the number.”
What this tool tells you
It separates the two things people conflate: how much of your ledger is fundable at all, and what percentage of that gets advanced. Most of the disappointment in invoice finance comes from the first, not the second. If concentration is what is costing you, the debtor concentration checker looks at that alone. If you want to know whether a provider is likely to take the case, the approval likelihood checker covers the underwriting signals instead.
Founder & Managing Director, Muswell Rose, founder and PSC of Best Business Loans Ltd
Adam is the founder and managing director of Muswell Rose and a founder of Best Business Loans Ltd, the company behind Market Invoice. He spent over three years as managing director of Penny, a UK invoice finance business, and his career runs through insurance, mortgages, commercial finance and fintech lending. He writes the Market Invoice library.
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