What it means
Banks fund themselves mainly through deposits and by borrowing from one another overnight. When a bank cannot cover an unexpected outflow or falls short on its required balances, it can borrow from the central bank instead, secured against collateral it has pledged in advance.
The price of that borrowing is the discount rate. There is not one rate but three tiers.
Primary credit goes to financially sound banks at the headline rate, secondary credit costs more and goes to institutions in weaker condition, and seasonal credit serves small banks with predictable agricultural or tourism cycles. When people say the discount rate without qualifying it, they almost always mean the primary credit rate.
The rate matters to ordinary businesses as a signal rather than as a direct cost, since almost no company borrows from a central bank. Set above the federal funds target, it caps how far the interbank rate can spike during a squeeze, which protects the funding plumbing that ultimately prices business overdrafts and credit lines.
Narrowing the gap between the two is a deliberate move to make emergency funding cheaper and more attractive. Use of the window carries a stigma that regulators have tried repeatedly to remove.
Borrowing there has historically been read as a sign of distress, so banks avoid it even when it is the cheapest option available, which blunts its usefulness in exactly the moment it is needed. Central banks now publish borrower names only after a long delay, partly to reduce that effect.
One point of confusion is worth clearing up early. The discount rate in this sense is a policy interest rate, and it has nothing to do with the discount rate used in discounted cash flow valuation, which is a company's cost of capital.
In practice
Real-world examples.
Example
A community bank loses a $30,000,000 municipal deposit with two days notice. Rather than sell securities at a loss into a weak market, it borrows at the discount window for ten days against pledged loans, then repays once a scheduled inflow arrives.
Example
A central bank cuts the spread between the discount rate and the federal funds target during a period of market stress, and simultaneously extends the maximum term from overnight to 90 days. The intent is to make the facility a genuine option rather than a last resort.
Example
A bank treasurer runs an annual test borrowing of $5,000,000 for one day, purely to confirm that collateral pledging and settlement mechanics work. The exercise costs a few hundred dollars in interest and removes the operational risk of a first attempt during a crisis.
Formula
Calculation
Interest cost = Principal x Rate x (Days / 360)
A regional bank borrows $50,000,000 through the discount window for 14 days at a primary credit rate of 5.50%. The interest is $50,000,000 x 0.055 x (14 / 360) = $2,750,000 x 0.038889 = $106,944.
Borrowing the same amount for the same period in the interbank market at 5.00% would have cost $50,000,000 x 0.050 x (14 / 360) = $2,500,000 x 0.038889 = $97,222. The premium for using the central bank facility is $106,944 - $97,222 = $9,722 over the fortnight, which is the price of certainty when interbank lenders will not quote.
If the central bank narrowed the spread from 50 basis points to 25 basis points, the premium would halve to $50,000,000 x 0.0025 x (14 / 360) = $4,861. That is precisely the lever policymakers pull when they want banks to use the facility rather than hoard cash.Case study
Seen in the real world.
The following is an illustrative and fictional example. Kestrel Valley Bank, an invented institution with $2,200,000,000 of assets, had never once used the discount window. Its board considered any borrowing from the central bank to be an admission of weakness, and its collateral had never been formally pledged.
During a period of deposit outflows across the sector, Kestrel Valley lost 7% of its deposits in three weeks. It needed roughly $80,000,000 of short-term funding. Because it had no pledged collateral in place, it could not access the window quickly, and it instead sold long-dated bonds at a realised loss of about $3,400,000. Had it borrowed $80,000,000 at a 5.50% discount rate for 30 days, the interest cost would have been $80,000,000 x 0.055 x (30 / 360) = $366,667.
After the episode Kestrel Valley pre-positioned $250,000,000 of loan collateral, tested the borrowing process twice a year, and wrote discount window access into its contingency funding plan as a normal tool rather than a confession. The illustrative point is that the stigma attached to the facility cost this fictional bank roughly ten times what using it would have.
Watch out
Common mistakes.
- Confusing the federal discount rate with the discount rate used in valuation. One is a central bank lending rate, the other is the rate used to bring future cash flows to present value.
- Assuming the discount rate is the main tool of monetary policy. The federal funds target and open market operations do most of the work, while the discount rate serves as a ceiling and a safety valve.
- Believing that borrowing at the window means a bank is failing. Sound institutions use it for short-term timing gaps, and regulators actively encourage them to treat it as routine.
Questions
People also ask.
Why is the discount rate set above the federal funds rate?
So banks turn to each other first and use the central bank only when normal markets are unavailable, which keeps the facility as a backstop rather than a subsidy.
What collateral does the central bank accept?
A broad range including government securities, agency debt and performing commercial and consumer loans, each valued with a haircut that reduces the amount that can be borrowed against it.
How does the rate change?
A regional reserve bank's board proposes it and the central governing board approves it, which usually happens alongside changes in the federal funds target.
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