Cash Sweep in an LBO: How It Deleverages Debt
A cash sweep applies excess free cash flow to prepay LBO debt early. See how it accelerates deleveraging, lifts equity returns, and gets modeled.
May 3, 2026 · 7 min read
A cash sweep in an LBO is the use of a company's excess free cash flow to prepay debt ahead of its scheduled maturity. After the borrower covers mandatory amortization and a minimum cash balance, the remaining cash is swept to pay down the most senior debt first. Wall Street Prep defines the cash sweep as the optional prepayment of debt using excess free cash flows in advance of the originally scheduled repayment date. In practice, a credit agreement also forces a mandatory excess cash flow sweep, so the term covers both required and voluntary prepayment. The cash sweep is what makes an LBO self-deleveraging, and faster deleveraging is one of the three core drivers of equity returns in a buyout.
TL;DR
- A cash sweep prepays LBO debt with excess free cash flow, ahead of the scheduled maturity date.
- Mandatory amortization on a Term Loan B is typically 1% of original principal per year, per IB Interview Questions.
- A mandatory excess cash flow sweep often directs 50% to 75% of excess cash to debt, stepping down as leverage falls.
- Sweeps repay debt by seniority: revolver first, then Term Loan A, then Term Loan B.
- Faster paydown cuts net debt at exit, which lifts equity value and the sponsor's IRR.
What is a cash sweep in an LBO?
A cash sweep is a mechanism that channels a leveraged company's leftover cash flow into early debt repayment. Wall Street Prep describes it as the optional prepayment of debt using excess free cash flow before the scheduled repayment date. The lender benefits because principal comes back faster, which lowers credit risk, and the equity holder benefits because lower debt means a larger equity slice at exit. Most LBO credit agreements pair this with a contractual excess cash flow sweep, so part of the sweep is required, not voluntary. The result is a structure that pays itself down: operating cash flow services interest, covers required amortization, and then attacks principal. This is why a buyout can generate returns even with no change in the purchase or exit multiple, as our walk me through an LBO guide explains.
How is the excess free cash flow calculated?
Excess free cash flow is the cash left after the business funds operations, taxes, capital expenditures, required debt service, and a minimum cash cushion. Breaking Into Wall Street frames the available pool as cash flow available for debt repayment (CFADR). The build is straightforward:
| Line | Effect |
|---|---|
| Beginning cash balance | Plus |
| Free cash flow for the period | Plus |
| Minimum required cash reserve | Minus |
| Mandatory principal amortization | Minus |
| = Cash available for the sweep (CFADR) | Result |
Whatever survives that waterfall is the pool the sweep can use. The precise definition of excess cash flow lives in the credit agreement, and IB Interview Questions notes that the exact wording materially affects how much cash the sponsor keeps versus hands to lenders. A tighter definition sweeps more cash to debt and deleverages faster.
How does mandatory amortization differ from the sweep?
Mandatory amortization is a fixed, scheduled principal payment, while the sweep is the variable prepayment that uses leftover cash. IB Interview Questions notes that a Term Loan B typically carries 1% annual mandatory amortization, meaning 1% of original principal is repaid each year and the remaining 99% is due at maturity. A Term Loan A amortizes faster, often 5% to 10% a year, and high-yield bonds are usually bullet maturities with no scheduled paydown at all.
The sweep sits on top of that. After the required 1% is paid, any qualifying excess cash is applied to prepay more principal. The credit agreement often steps the mandatory sweep percentage down as the company deleverages. IB Interview Questions cites a common grid: 75% of excess cash flow swept above 4.0x leverage, 50% between 3.0x and 4.0x, and 25% or none below 3.0x. This rewards the borrower for paying down debt.
In what order does the cash sweep repay debt?
The sweep follows the capital structure by seniority, repaying the most senior, cheapest debt first. Breaking Into Wall Street and IB Interview Questions both lay out the same waterfall: the revolver is repaid first, then term loans (Term Loan A before Term Loan B), then senior unsecured notes, then any subordinated or mezzanine debt. Each junior tranche only receives sweep cash that survives the tranches above it.
To prevent overpaying, the model wraps each tranche in a MIN function. Breaking Into Wall Street gives the logic as MIN(remaining debt balance, CFADR times the sweep percentage). If 100 dollars of cash is available at a 50% sweep and 500 dollars of debt remains, the model repays 50 dollars. If only 40 dollars of debt is left, it repays 40, not 50, so the balance never goes negative. For subordinated tranches, the formula subtracts senior repayments first, so a Term Loan B sweep only draws on cash that the revolver and Term Loan A did not absorb.
How does the cash sweep boost equity returns?
The sweep lifts equity returns by shrinking net debt at exit, which is the single largest lever in many buyouts. IB Interview Questions illustrates this with a clean example: paying down 250 million dollars of an initial 500 million dollars of debt over five years increases equity value by 250 million dollars at exit, even if enterprise value never changes. That gain accrues entirely to equity, because lenders only get their principal and interest back.
There is a second, smaller effect. Every dollar of debt repaid early reduces future interest expense, which frees up more cash flow for the next period's sweep and compounds the paydown. Breaking Into Wall Street notes the equity boost from lower interest is modest next to the deleveraging effect, but it is real. The mechanics behind this paydown engine are exactly what a paper LBO tests under time pressure, and why leveraged finance bankers spend so much time on downside debt schedules.
Frequently Asked Questions
Is a cash sweep mandatory or optional in an LBO?
It is both, depending on the clause. The pure cash flow sweep that Wall Street Prep and Breaking Into Wall Street describe is the optional prepayment of debt with excess cash. Separately, most credit agreements contain a mandatory excess cash flow sweep that forces the borrower to apply a set percentage, often 50% to 75%, of excess cash to debt. So a real LBO has a required floor plus an optional layer on top.
What percentage of cash flow gets swept?
It depends on leverage and the credit agreement. IB Interview Questions cites a typical grid where 75% of excess cash flow is swept above 4.0x leverage, 50% between 3.0x and 4.0x, and 25% or zero below 3.0x. Simple interview models often assume a 100% sweep of all available cash, while real deals cap senior sweeps around 50% to balance lender and sponsor interests.
Why does a cash sweep increase equity value?
Because debt repaid during the hold reduces net debt at exit, and a lower net debt means a bigger equity stub when you bridge from enterprise value to equity value. IB Interview Questions shows 250 million dollars of debt paydown turning directly into 250 million dollars of added equity value at exit, with no change in operations or multiple.
Does a cash sweep hurt the lender's return?
Not really. Breaking Into Wall Street points out that prepayment lowers a lender's total interest income, but because the outstanding principal falls in step, the annualized IRR holds roughly flat. Lenders also build in call protection and prepayment penalties on some tranches to manage reinvestment risk.
How do you model a cash sweep without circular references?
You cap each prepayment with a MIN function so the sweep never exceeds the remaining balance, and you handle the interest-on-cash circularity with a circularity switch or by toggling iterative calculation. Breaking Into Wall Street recommends consolidating optional repayments into a single schedule when a deal has three or more tranches, which keeps the formulas clean.
What is the difference between a cash sweep and mandatory amortization?
Mandatory amortization is the fixed, scheduled principal payment written into the loan, like 1% per year on a Term Loan B. The cash sweep is the variable prepayment that uses leftover cash flow after amortization. Amortization is contractual and constant; the sweep flexes with how much excess cash the business throws off.
Sources
- Wall Street Prep: LBO Cash Sweep (checked June 2026)
- Breaking Into Wall Street: Cash Flow Sweep in LBO Models (checked June 2026)
- IB Interview Questions: LBO Debt Schedule, Amortization, and Cash Sweeps (checked June 2026)