The LBO Cash Sweep Explained: How a Buyout Actually Pays Down Its Own Debt — Mandatory Amortisation, the Excess-Cash-Flow Sweep, the Revolver Plug, and the Circular Reference Every Model Breaks On

An LBO Delevers in One Tab, and Most Candidates Cannot Build It

A buyout return splits three ways — EBITDA growth, multiple change, and debt paydown — and the third one is the only one that happens mechanically, on its own, inside a single worksheet. That worksheet is the debt schedule, and it is the part of an LBO model that separates a candidate who has drawn a returns bridge on a napkin from one who can actually run cash through a capital structure and watch the leverage fall.

The reason it trips people up is that it is genuinely circular and genuinely ranked. Cash does not simply "pay down debt"; it is applied in a strict order, against a strict set of rules, to a strict number that the schedule itself helps compute. Get the order or the number wrong and the model either understates the equity return or, more embarrassingly, throws an error and stops. This is the tab a modelling test is really checking.

Cash Flow Available for Debt Service Is the Only Input That Matters

Everything downstream is a claim on a single figure: the cash the business throws off after it has paid to keep running and to service what it owes. Build it from the top. Take EBITDA, subtract cash interest, subtract cash taxes, subtract capex, and subtract the increase in net working capital. What is left is cash flow available for debt paydown — the pool the schedule then rations.

A clean, round example carries the mechanics better than prose. A business bought for 10x £100m of EBITDA — a £1,000m enterprise value — financed with 5.0x of term debt, so £500m of Term Loan B and a £75m revolver undrawn at close. In year one the pool builds like this, and the numbers are illustrative benchmarks, not a specific deal:

£27m against £500m of debt is a 5.4% paydown rate before a single rule is applied. That figure — how fast the pool can eat the balance — is the number that decides how much of the eventual return comes from delevering, and it is far lower than the marketing implies. Now the schedule rations it.

Mandatory Amortisation: Paid First, and Smaller Than You Think

The first claim on the pool is contractual: the mandatory amortisation the loan documents require regardless of how the business performs. For a US institutional Term Loan B this is the market-standard 1% of original face per year, repaid in quarterly instalments, with the remaining ~93% due as a bullet at the seven-year maturity. On £500m that is £5m a year — deliberately trivial, because TLB investors want yield and duration, not their principal handed back early.

In Europe the convention is softer still: many institutional term loans amortise at nil, structured as pure bullets. So the "mandatory" leg of the schedule, the part that is guaranteed to happen, barely moves the balance. It is the sweep — the discretionary leg — that does the delevering, and it is the part sponsors negotiate hardest.

The Excess-Cash-Flow Sweep: The Rule That Actually Cuts Leverage

After mandatory amortisation is paid, a portion of the cash that remains is swept — used to prepay term debt above and beyond the required schedule. This is the excess-cash-flow sweep, and it is the single mechanic that turns operating cash into falling leverage. The sweep percentage is set by a grid tied to the leverage ratio, and the classic shape is a step-down: 50% of excess cash flow swept while net leverage sits above a threshold, 25% as it falls through a middle band, and 0% once the business is deleveraged below a floor.

Return to the example. Of the £27m pool, £5m goes to mandatory amortisation, leaving £22m. At a 50% sweep, £11m is prepaid against the term loan and £11m drops to the balance sheet as cash. Total year-one paydown is £16m — the £5m required plus the £11m swept — taking the term loan from £500m to £484m. The sweep, not the amortisation, is two-thirds of that.

One qualifier sits underneath the sweep: the minimum cash balance. A model does not sweep every last pound; it holds an operating cash buffer — a fixed figure, or a percentage of revenue — and sweeps only what sits above it. Miss that buffer and the model will happily drive cash to zero and start throwing the business into a liquidity hole it would never run in practice. Which raises the mirror problem: what happens when the pool is negative.

The Revolver Is the Plug — Drawn on a Shortfall, Repaid First on a Surplus

Not every year produces positive cash. A working-capital swing, a bolt-on, a soft trading period, and cash available for debt service turns negative. The revolving credit facility exists for exactly this: it is drawn to fund the shortfall and hold the minimum cash balance, and it is repaid ahead of the term loan the moment cash turns positive again. In the mechanics of a model the revolver is the plug — the balancing item that keeps cash from ever falling below the floor.

That ordering matters and is testable. The revolver sits at the top of the repayment waterfall precisely because it is the facility the business relies on for liquidity; a sponsor pays it down first to keep the undrawn capacity available. So the applied-cash logic in the schedule is a cascade: pay mandatory amortisation, repay any revolver drawings, then sweep the remainder against the term loan — and if the pool is negative, draw the revolver to cover it. Build that cascade wrong and the balances stop reconciling.

The Circular Reference: Why Half the Modelling Tests Break Here

Here is the trap the tab is built around. Interest expense should be charged on the average of the opening and closing debt balance for the year — because the debt is being paid down through the year, charging interest on the opening balance overstates it. But the closing balance depends on how much was swept, the sweep depends on cash available after interest, and interest depends on the average balance. Interest → cash flow → paydown → closing balance → average balance → interest. The model is chasing its own tail.

Charging interest on the opening balance is the tempting shortcut, and it is wrong in a way a good examiner spots instantly — it overstates interest, understates cash, understates paydown, and drags the equity return. The circularity is not a bug to be avoided; it is the correct treatment, and handling it cleanly is the tell of someone who has built the schedule rather than read about it.

The Schedule, End to End

Put the pieces in sequence and the debt schedule runs the same way every year:

Five steps, one circular loop, and a leverage ratio that falls a little each year. Run it across a five-year hold and the debt paydown line of the returns bridge writes itself — which is exactly where the honest question about its size comes in.

The Verdict: Debt Paydown Is the Return Driver Juniors Overrate

The debt schedule is satisfying to build because it feels like the engine of the return — cash goes in, leverage comes down, equity value compounds. But look at the arithmetic. A 5.4% pool against the balance, a mandatory leg near zero, and a sweep grid that steps down to nothing as leverage falls: the schedule delevers slowly, and it delevers least in the later years when the leverage ratio has already dropped through the grid. In a high-entry-multiple, cov-lite market where sponsors negotiate the sweep down and hold cash for bolt-ons and recaps, the debt-paydown contribution to a modern buyout return has quietly shrunk.

That is the view worth carrying into an interview. The value-creation bridge has three legs, and the mechanical one is increasingly the smallest — the returns that matter are made in EBITDA growth and, when the market cooperates, multiple expansion. A candidate who builds a flawless debt schedule and then says "and this is where most of the return comes from" has built the model correctly and misread it. The schedule is the plumbing; it is not the profit.

Careers: The Debt Schedule Is the Associate's Tab

On a live model the debt schedule is almost always the analyst's or associate's to own, and it is where the senior person looks first when the equity return "feels wrong". A junior who can trace a broken return back to a mis-ranked waterfall, a missing minimum-cash buffer, or interest charged on the opening balance is doing the part of modelling that cannot be faked. The circularity switch, the sweep grid, the revolver plug — these are not interview trivia; they are the daily mechanics of turning a signed capital structure into a set of projected returns the investment committee will actually see.

The skill that compounds is knowing which assumption the schedule is most sensitive to. Flex the sweep percentage or the entry leverage and watch the equity IRR move; flex EBITDA growth and watch it move more. An associate who can say "the return is barely sensitive to the sweep but highly sensitive to exit multiple" is reading the model the way an investor does — the same instinct that separates a real analysis from a tab that merely balances.

Take Your Preparation Further

The debt schedule sits on top of the rest of the LBO, so read it alongside the pieces that build the structure it delevers. Start with the LBO debt stack for the term loan, revolver and where each sits in the capital structure, and debt covenants and cov-lite for why the sweep grids have loosened. For the cash-flow number that feeds the schedule, see unlevered free cash flow and EBITDA to free cash flow; for what the delevering is worth against the other return drivers, the value-creation bridge. Then rehearse building the whole thing under time pressure with how to prepare for an LBO modelling test.

For a ready-built schedule you can pick apart line by line, download the LBO Model Template, and for the valuation methods that set the entry and exit multiples on either side of it, the free Valuation Methods Cheat Sheet.

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