Borrowing Base

A borrowing base is the pool of collateral that limits how much a lender will advance on a revolving loan. The borrower and lender agree on it in the loan agreement, and it rises and falls as the collateral changes. It is most common in asset-based lending (ABL), but lenders also use it for other revolving lines, such as credit lines for homebuilders.

The calculation has three steps. First, remove collateral that doesn't qualify. Second, multiply what's left by the advance rate for each type of collateral. Third, subtract reserves. Then compare the result with what the borrower already owes:

Availability = (eligible collateral × advance rate) − reserves − loan balance

Here is an example with round, hypothetical numbers. A company reports $1,200,000 of receivables. Of that, $200,000 is badly past due and doesn't qualify, leaving $1,000,000. At an 85 percent advance rate, the base is $850,000. A $50,000 dilution reserve brings it to $800,000. With $700,000 already drawn, the company can borrow $100,000 more.

Why it matters for lenders

The borrowing base is the lender's main defense on a revolving line. A business line of credit without one depends almost entirely on the borrower's cash flow. With one, the credit shrinks when the collateral shrinks. That only works if the numbers are accurate and current.

The borrower reports its base on a signed borrowing base certificate, usually weekly or monthly. Lenders test it against aging reports, bank statements and field exams. Common exclusions include invoices past due by about three times their payment terms, amounts owed by affiliated companies, contra accounts (customers who are also suppliers), and any single customer above a set share of the total. When the loan balance runs above the base, the gap is called an over-advance, and the agreement usually requires a quick paydown. Borrowing base terms often sit beside loan covenants the borrower must also meet.

How it works in practice

Early each month, a manufacturer uploads its receivables aging, inventory report and a signed certificate. The lender's analyst recalculates eligibility from the raw aging instead of trusting the borrower's totals. She flags one customer that now makes up nearly a third of all receivables, applies the concentration limit, and updates the dilution reserve using the last six months of credit memos. Availability falls by $40,000. The borrower gets the updated figure, and the next advance request is checked against it.

When this lives in spreadsheets, staff rebuild the same workbook every month, formulas break, and the advance rates in use drift from the ones in the loan agreement. Tying each certificate to the loan record keeps a clean history and shows early when a borrower is trending toward its limit.