Part 1 · Underwriting the treaty year · 🟢 Easy · ~40 min
🧭 In the product
From the dashboard: open ReinsuranceDemo → Submissions → card Alpina MTPL XL 2027 (📬 the renewal) → tab Structure. Then walk sideways: Tower and Economics in the same row of tabs.
📖 Theory
At renewal, one submission arrives per programme: cedent Alpina Versicherung AG (St. Gallen — its German motor branch writes MTPL in EUR), broker Cartwright Re, programme MTPL, inception 2027-01-01, term 12 months. In the product this is one Underwriting/Submission node, and everything the desk does starts from what it stores:
- The tower — the layers as data rows. For 2027: Layer 1 = 7m xs 3m at 7.8% rate on line, Layer 2 = 15m xs 10m at 3.4%, our offered share 50% on both. All figures EUR.
- The stated economics — subject premium 127.5m, stated loss ratio 0.72, brokerage 0.10, ceding commission 0, expense ratio 0.06. Stated means: the cedent's pack said so; the product stores it as a fact about the pack, not as truth.
- The reported claims bordereau — the cedent's loss statement as of 2026-06-30, one row per claim. It becomes the whole of Lesson 9.
- A stored lifecycle status —
Under assessment. Stored, never derived: a page may group by status, it never invents one.
Reading a submission critically means separating the stated from the derived. The product derives, per layer, premium at 100% = rate on line × limit, and across the tower the blended rate on line and the projected combined ratio CR = loss ratio + brokerage + ceding commission + expense ratio — only when every component is on file. A missing figure stays null and surfaces as a data-quality referral; it is never silently read as zero. That null-honesty is the first product principle you will meet again in every lesson.
⚡ Experience it
The 2027 tower, derived exactly as the product's Economics area derives it. Run it, then check the numbers against the live page.
Show the Alpina MTPL XL 2027 tower — Layer 1 = 7m xs 3m at 7.8% RoL, Layer 2 = 15m xs 10m at 3.4%, offered share 50% on both — as a data grid deriving each layer's premium at 100%, our share of it, and underneath the tower totals: premium at 100%, blended rate on line, our gross line and our premium, plus the projected combined ratio from LR 0.72 + brokerage 0.10 + expense 0.06.
✍️ Your turn
Difficulty: 🟢 Easy — 10 minutes
Predict before you run: Layer 1's premium at 100% is 0.078 × 7,000,000. What is Layer 2's — and what do the two make together? Change rateOnLine for Layer 2 to 0.04 in the cell above, re-run, and check the blended rate on line moves from 4.8% to exactly 5.209% (1,146,000 / 22,000,000).
Then compare vintages in the worked demo — the 2026 bound year next to the 2027 ask, and the rate change between them.
Now make it yours — three graded exercises » (🟢 read the tower · 🟡 the rate change · 🔴 the missing figure, each with a worked solution).
Check yourself
Quick questions on this lesson — instant feedback and a score.
Course home: Reinsurance in Practice · Next: Lesson 2 — The rulebook as data »