Cash Waterfall

Definition¶

A cash waterfall is the contractually defined priority sequence in which a project's available cash is allocated across its obligations. It specifies, step by step, which payments are made first and which are only paid after higher-priority obligations are fully satisfied. In project finance, the cash waterfall is set out in the financing documents (the common terms agreement, the intercreditor agreement, and the accounts agreement) and is replicated in the financial model.

The term "waterfall" reflects the visual and conceptual image of cash flowing downward through successive tiers: if there is enough cash to fill the top tier (the most senior obligation), the excess flows to the next tier, and so on until either all tiers are filled or the cash is exhausted.

Standard Waterfall Sequence¶

A standard project finance cash waterfall allocates cash in the following sequence:

1. Operating costs — all operating and maintenance expenditure required to keep the project running
2. Senior debt interest — interest payable on the senior secured debt facility in the period
3. Scheduled senior debt principal repayment — the scheduled principal repayment (whether flat, annuity, or sculpted) due in the period
4. Debt service reserve account (DSRA) funding — cash required to top up the DSRA to its required balance (typically six months' projected debt service)
5. Cash sweep or additional repayment — any additional principal repayment required by the cash sweep mechanism
6. Subordinated debt service — if applicable, interest and principal on subordinated debt
7. Maintenance reserve funding — contributions to the lifecycle maintenance reserve
8. Equity distributions — any remaining cash available for distribution to equity investors, subject to the distribution test (typically a minimum DSCR being satisfied for the period and on a trailing basis)

The Waterfall in the Financial Model¶

The financial model replicates the cash waterfall row by row, with each level of the waterfall calculated as a separate line item. The DSCR is calculated as the ratio of Cash Available for Debt Service to the sum of interest and scheduled principal repayment (step 1 above, divided by the sum of steps 2 and 3).

A distribution lock-up test is applied at the equity distribution step: if the DSCR in the current period or on a trailing average basis is below the minimum required, the distribution step is locked and the cash remains in the project account.

Common Modelling Errors¶

• Applying the DSCR test at the wrong point in the waterfall (for example, before interest rather than after)
• Omitting DSRA topping-up from the waterfall sequence or placing it at the wrong priority level
• Calculating the distribution test DSCR using the wrong cash flow definition
• Misaligning the waterfall period (monthly, quarterly, semi-annual) with the debt service period

Further Reading¶

• World Bank, PPP Reference Guide, World Bank Group
• IFC, Project Finance in Developing Countries, International Finance Corporation

Continue Reading¶

Prerequisites¶

• Project Finance Model Audit — the parent pillar

Related Technical Guides¶

• Debt Sculpting Mechanics — the technique for sizing the principal repayment step in the waterfall

Related Glossary¶

• DSCR — the coverage ratio calculated within the waterfall
• Debt Service — the senior obligations that are the highest-priority cash application after operating costs
• Availability Payment Model — a structure whose revenue feeds into the top of the waterfall

Related Products¶

• Financial Model Audit Engine (FMAE) — deterministic structural auditing referenced throughout this guide