The 13-Week Cash Forecast

The 13-week cash forecast is the operational cash management tool — a rolling weekly projection of cash inflows and outflows for the next quarter. It is more granular than the annual cash model and more actionable: it tells you exactly which weeks are tight, where the peaks and troughs occur, and whether you need to take action in the next 30 days. Every CFO should review the 13-week forecast weekly. Every CEO should review it monthly.

13-Week Cash Forecast (Weeks 1-6 shown):
──────────────────────────────────────────────────────
            Wk 1    Wk 2    Wk 3    Wk 4    Wk 5    Wk 6
──────────────────────────────────────────────────────
Opening:   $2.4M   $2.3M   $2.1M   $1.8M   $2.2M   $2.1M

Inflows:
 Collect.  $180K   $140K   $120K   $580K   $160K   $130K
 Prepays    $0K     $0K    $85K     $0K     $0K    $120K
──────────────────────────────────────────────────────
Total In:  $180K   $140K   $205K   $580K   $160K   $250K

Outflows:
 Payroll    $0K     $0K     $0K   ($280K)   $0K     $0K
 Vendors  ($95K)  ($80K) ($110K)  ($70K)  ($85K)  ($90K)
 Rent       $0K     $0K     $0K     $0K     $0K   ($45K)
 Other    ($35K)  ($25K)  ($20K)  ($30K)  ($25K)  ($20K)
──────────────────────────────────────────────────────
Net Flow:   $50K    $35K    $75K   $200K    $50K    $95K

Closing:   $2.3M   $2.1M   $1.8M   $2.2M   $2.1M   $2.0M

[ALERT] Week 3: lowest cash point at $1.8M.
Monitor and ensure Wk 4 collections arrive.

1. Build from Known Commitments Start with fixed outflows: payroll dates, rent, loan payments, subscription renewals. Then add variable outflows: vendor payments based on purchase orders, estimated tax payments, one-time expenses. Fixed outflows are highly predictable. Variable outflows require invoice-level detail for the next 4 weeks and estimates for weeks 5-13.
2. Layer in Collection Estimates Apply the collection timing model from Lesson 2 to booked revenue. Weight near-term collections (weeks 1-4) by invoice-level certainty. Weight mid-term collections (weeks 5-8) by segment patterns. Weight longer-term collections (weeks 9-13) by historical averages. Accuracy degrades with horizon — which is why the forecast rolls weekly.