Debt service forecasting in a 13-week cash flow model
Debt payments are fixed obligations. They land on specific dates, in specific amounts, regardless of what else is happening in the business. This is how I approach them — what gets collected, how it is structured, and what gets monitored each week.
When building a 13-week cash flow forecast, debt service is one of the first things to map. It has to be. A loan repayment or interest payment does not negotiate — it lands on the date in the agreement. If the forecast does not have it in the right week, the ending cash figures are wrong from the beginning.
What follows is a standard working approach: what information to collect, what to build from it, and what to watch throughout the 13 weeks.
The debt register
The starting point is a complete list of all current debt — every loan, credit facility, lease, and factoring arrangement the business has. If that list does not exist in a usable form, it gets built from the loan agreements directly.
This is the debt register: a simple spreadsheet, one row per facility, that becomes the source of truth for everything that follows in the forecast.
- Lender name and type of facility
- Total facility limit and current outstanding balance
- Interest rate — fixed or variable, and the margin if variable
- Repayment schedule (structure, frequency, amounts) with link to detailed table
- Final maturity date
- Fees: commitment fees, prepayment penalties, arrangement costs
- Prevents payments from being missed or double-counted in the model
- Drives the weekly payment rows in the 13-week forecast
- Feeds covenant monitoring and refinancing risk analysis
- Gives management a single place to see total debt obligations
The register is updated every week with actual balances after payments are made. A register that is a month out of date is not useful — it creates false confidence.
Different facility types behave differently in the model. Each type is handled according to how it actually moves cash.
Term loans
Term loans produce fixed repayment outflows on predictable dates.
Revolving credit lines
Revolving credit lines affect both sides of the cash flow forecast. Drawdowns count as cash inflows, while repayments and interest create outflows. Available headroom also changes every week.
Leases
Leases are modelled as fixed monthly amounts. The payment is split into a principal-equivalent component and an interest component, because the two are treated differently for covenant calculations.
Factoring arrangements
Factoring appears as an advance received against invoices. There is no principal repayment. Instead, a discount fee is deducted, reducing the cash the business actually receives from its collections.
The payment calendar
Once the debt register is complete, the next step is to build a detailed payment calendar — a dedicated worksheet that translates all debt obligations into exact weekly cash outflows for the forecast period.
This intermediate step is important for several reasons:
- It forces accuracy — every payment is taken directly from the loan agreements rather than approximated or remembered.
- It makes it easy to spot timing issues (payments falling on different days of the week, rate resets, balloon payments, etc.).
- It keeps the main cash flow forecast clean and formula-driven instead of cluttered with dozens of individual debt lines.
- It serves as an important audit trail and management tool — a single place where you can see all upcoming debt service at a glance. This creates a clean chain: Loan Agreements → Debt Register → Payment Calendar → Cash Flow Forecast.
Columns typically include: week number, exact date, lender, facility type, principal due, interest due, fees, and total cash outflow. The cash flow model then pulls these figures automatically using formulas (e.g. SUMIFS), rather than hard-coding or lumping everything into one generic “debt repayment” line.
Separating principal, interest, and fees is especially valuable because they often fall on different dates and are treated differently for covenant testing, tax, and lender reporting.
One detail worth checking for every amortising loan is the interest component of each repayment. In most cases, the interest is highest at the beginning of the loan and gradually decreases as the outstanding balance is repaid. If a client's accounting records show the same interest expense every month for a reducing-balance loan, this may indicate that the repayment schedule has not been maintained correctly. The lender's amortisation schedule provides the correct allocation of interest and principal for each payment.
Rate reset dates for variable-rate facilities are noted in the calendar. If a reset falls within the 13-week window, the interest calculation changes from that week onward.
Monitoring financial covenants
Loan agreements may contain financial covenants — minimum performance levels the business must maintain. Breaking a covenant is a technical default, even if every payment has been made on time.
Covenant headroom is tracked alongside the cash position. The connection is direct: the conditions that create cash pressure — declining revenues, slower collections, higher costs — are often the same conditions that push financial ratios toward breach thresholds. Monitoring both in the same weekly review allows problems to be spotted earlier.
A covenant summary sits alongside the debt register: one row per covenant, showing the required level, the testing frequency, and current headroom. It is reviewed every week as part of the forecast update.
| Covenant type | What it tests | Why it matters in the forecast |
|---|---|---|
| Leverage ratio | Total net debt relative to EBITDA | If EBITDA is falling, this tightens even without new borrowing |
| Interest coverage | EBITDA relative to interest expense | Rising rates or falling earnings shrink headroom quickly |
| Fixed charge coverage | Operating cash flow (cash made from everyday business) relative to all fixed obligations | Directly linked to the cash flows already being modelled |
| Minimum liquidity | Cash balance or current ratio | The forecast ending cash figure is the direct test of this |
| Minimum net worth | Total equity on the balance sheet | Losses in the period reduce headroom alongside the P&L |
A covenant breach discovered at the lender’s test date is a more difficult conversation than one identified two or three weeks earlier through the forecast. If headroom is visibly shrinking in week 4, management has time to act before the quarterly test in week 10. That is the practical value of monitoring covenants in the same tool as the cash position.
Non-financial covenants also get checked — reporting deadlines, insurance requirements, restrictions on selling assets. Missing a reporting deadline is itself a breach in most agreements. These dates go into the 13-week calendar so preparation starts early enough to meet them without pressure.
Refinancing risk within the 13 weeks
Refinancing risk is the possibility that debt maturing within the forecast period cannot be renewed or replaced — or can only be replaced on materially worse terms. In a 13-week model this risk is concrete: a facility that matures in week 8 with no confirmed replacement creates a large cash outflow with no matching inflow.
The debt register is reviewed for any facilities that mature or require renewal within the 13 weeks. This includes:
- Term loans reaching their final repayment date, particularly those with a balloon payment at maturity
- Revolving facilities that must be fully repaid at a set date before renewal can occur
- Revolving facilities with a clean-up provision — a requirement that the outstanding balance reaches zero for a specified number of consecutive days during the year. If that period falls within the forecast window, the paydown creates a cash outflow in a specific week
- Finance leases coming to end of term where renewal or buy-out terms are not yet confirmed
Where refinancing risk exists, available backup options are documented realistically: unused capacity on other facilities, cash reserves, receivables available for factoring, shareholder support. Speculative refinancing that has not been confirmed is not included as a certain inflow in the base forecast. The base forecast is built without it — showing the gap clearly — and a separate scenario shows what changes if the refinancing is confirmed. Management sees both positions.
Interest rate assumptions
For fixed-rate facilities, there is no assumption to make. The payment is the same every period and comes directly from the loan agreement.
For variable-rate facilities, the rate is typically a market benchmark — such as EURIBOR or the base rate — plus a fixed credit margin agreed in the loan contract. The margin does not change. The benchmark changes at each reset date.
Every reset date is noted in the payment calendar. If a reset falls within the 13-week window, the interest calculation changes from that week onward. The old rate is not carried past the reset date.
Credit line availability and the borrowing base
For many asset-based revolving credit facilities, the amount that can be borrowed is not simply the facility limit minus the amount already drawn. Instead, it depends on the borrowing base.
The borrowing base is a calculation that determines how much the lender is willing to lend against eligible assets, usually trade receivables and sometimes inventory. As the value of these assets changes, the amount available to borrow changes as well.
Not every revolving credit facility works this way. Some traditional cash flow revolvers are limited only by the agreed facility limit and compliance with financial covenants.
If the facility uses a borrowing base, it should be updated regularly, often every week. As customers pay invoices, new sales are made, and amounts are borrowed or repaid, the borrowing base changes. If customer payments slow down, fewer receivables may qualify as security, reducing the amount that can be borrowed. This often happens when extra cash is needed most. Finding this out in week 3 gives time to react. Finding out in week 9 may be too late.
The loan agreement defines which assets are eligible. Common exclusions from eligible receivables include:
- Invoices outstanding beyond a set number of days (typically 90 days from due date).
- Receivables from customers who are also suppliers to the business (contra-balances).
- Receivables concentrated in a single customer beyond an agreed percentage of the total.
- Disputed invoices or receivables subject to set-off rights.
Available capacity each week is: borrowing base minus current outstanding draw minus any reserves or blocks specified in the agreement. This figure is updated weekly and reviewed alongside ending cash to give a realistic picture of accessible emergency liquidity.
Planned drawdowns and new facilities
The forecast includes not only scheduled repayments but also any planned inflows from borrowing — drawdowns on existing facilities or new financing expected within the 13 weeks.
A conservative approach is applied here. Planned borrowings under the revolving credit facility are included only to the extent they are within the current borrowing base. New credit lines or extension agreements under negotiation are not reflected in the baseline forecast as guaranteed receipts. The forecast is constructed without them — which reflects the actual cash position — and a clearly labelled reserve line item shows the effect if funding is confirmed.
A forecast that relies on uncommitted financing to close a cash gap is not a forecast — it is a wish. Management needs to see the gap clearly to make decisions. If the financing arrives, the position improves. If it does not, management has already started working on alternatives rather than discovering the problem the week the facility was expected to close.
Scenarios and sensitivity
Each week the forecast is run under at least two scenarios. The base case uses realistic assumptions for collections, costs, and debt service. The downside case applies stress to two or three variables simultaneously — for example, customers paying later than expected, costs coming in higher than planned, or a large payment falling due in the same week as a gap in receipts. Ending cash is calculated for each week under both.
Contingent obligations are listed separately — personal guarantees, guarantees for subsidiary debt, performance bonds. These do not appear in the base forecast because they are not certain outflows. If a trigger event becomes likely during the 13 weeks, the relevant amount moves into the main model immediately.
Compliance and lender reporting
Loan agreements typically include reporting obligations alongside financial covenants — deadlines by which compliance certificates, management accounts, or borrowing base certificates must be delivered to the lender. Missing a reporting deadline is itself a breach in most agreements, even if all payments have been made on time.
These deadlines go into the 13-week calendar alongside payment dates. Preparing a compliance certificate takes time — collecting actual numbers, running the calculations, getting management sign-off. Building the deadline into the forecast window means that work starts early enough to be done properly.
At the start of each week, actual cash flows from the week just completed are compared to what was forecast for that week. Where there is a material difference, the reason is identified and the remaining weeks of the forecast are updated accordingly.
If the variance is significant — a major collection that did not arrive, a payment larger than expected — it is flagged for management and, where necessary, the lender is informed promptly. Proactive communication with lenders, before they ask questions, consistently produces better outcomes than reactive explanations after the fact.