GIRateEngine — Motor Comprehensive Rating Methodology

How the premium gets calculated

GIRateEngine loads every Motor Comprehensive tariff table into memory once, then prices every quote from Aggregators, the website, POS, and the mobile app entirely in RAM — no database call on the request path. This is the plain-language walkthrough of what it computes today, and an honest map of what's still outstanding.

Basic Premium — implemented & verified Additional Covers & VAT — implemented 2026-07-30 Reflects PremiumCalculation.GetPremium_Comp, reviewed against SPGI_ACIG_GetPremium_Comp_Tameeni, 2026-07-30

✓

Additional Covers and VAT were closed on 2026-07-30. The engine now prices the Basic Premium (§2–3), every eligible Additional Cover (§4), and VAT on both — the three pieces a channel needs for a complete, billable quote. What's still open (Comprehensive CAP, Cross-Sell/Multi-Vehicle discounts, Motor Scheme Discount cap, region-resolution and minimum-premium reconciliation) is scoped in §5 and is no longer a go-live blocker on its own.

See Project Details.md for the full gap analysis and a phased go-live plan.

01 — Overview

Three pieces make up a quote

A Motor Comprehensive premium is the Basic Premium, minus discounts down to a protected floor, plus whatever Additional Covers the customer selects, plus VAT. GIRateEngine now computes all three pieces.

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flowchart LR
    A["Basic Premium
tariff + 13 loadings + TPL floor"]:::book --> C{"Discounts +
Minimum-Premium Floor"}:::blend
    C --> D["NetGross
base policy premium"]:::mid
    D --> E["+ Additional Covers
priced per eligible cover"]:::book
    E --> V["+ VAT
flat % per product"]:::book
    V --> F["Final Premium
what the customer pays"]:::final
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"Basic Premium" here means the mandatory base policy cost — third-party + own-damage cover on the vehicle itself. It is not optional. Additional Covers are everything the customer chooses to add on top: Personal Accident benefits, geographic driving extensions, replacement-vehicle cover, and similar.

02 — Basic Premium

The mandatory base premium Implemented

Every quote starts by picking the right tariff row, comparing it against a TPL-only floor, then loading it up by thirteen independent factors — one per rating dimension of the vehicle, the insured, and the policy.

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flowchart TD
    S0["Tariff lookup
Policy Type · Product · Scheme · Vehicle Group ·
Usage · Repair Type · Vehicle-Age band · SI band · Region"]
    S1["Basic Premium = MAX( Rate × SI ÷ 100, TPL-floor premium, Tariff Min Premium )"]
    S2["× 13 Loadings
Gender · Marital · Ins.Age · Nationality · BodyType · City ·
Profession · Usage · Region · Deductible · RepairType · NCD · SumInsured"]
    S3["+ Accident/Claims Loading
(only if prior accidents declared)"]
    S4["= NRP"]
    S5["÷ (1 − Applicable Loading %)"]
    S6["= Gross"]
    S0 --> S1 --> S2 --> S3 --> S4 --> S5 --> S6

Step 1 — Pick the tariff row, then floor it against TPL

The cached Comprehensive tariff set is filtered down to the exact combination of Policy Type, Product, Scheme, Vehicle Group, Usage, Repair Type, the vehicle's age band, its Sum-Insured band, and (if the caller selected one) a specific region — one row survives per deductible option. If no region was pinned by the caller, the engine resolves one from Address / National-ID / Vehicle-Registration region codes, requiring exactly one of the three to repeat before it trusts the result.

Basic Premium

Basic Premium = MAX( Tariff Rate × Sum Insured ÷ 100, TPL Premium × (1 + Min-Premium-Config %), Tariff's own Minimum Premium )

Comparing against a TPL-only floor guarantees a Comprehensive policy is never quoted cheaper than the mandatory Third-Party cover it already includes.

Step 2 — Thirteen loadings build the NRP

Each loading is a percentage of the Basic Premium, looked up independently and summed — not compounded:

Loading	Keyed by
Gender	Insured's gender
Marital Status	Insured's marital status
Insured Age	Insured's age band
Vehicle Nationality	Vehicle's nationality code
Body Type	Vehicle body type
Registration City	Vehicle registration city
Profession	Insured's profession/occupation
Use of Vehicle	Declared vehicle usage
Region	Vehicle registration region
Deductible	Selected deductible band
Repair Type	Agency vs. Non-Agency repair
NCD (as a loading)	Claim-free years
Sum Insured	Sum-insured band

A fourteenth, conditional loading applies only when the request declares prior accidents: Accident/Claims Loading, keyed by Product, Source Channel (Aggregator/Online/POS), Vehicle Usage, number of claims, and a liability ratio, with the same kind of "closest match, falling back to a wildcard" logic as the other lookups.

NRP & Gross

NRP = Basic Premium + Σ(loading amounts) + Accident Loading amount Gross = NRP ÷ (100 − Applicable Loading %) × 100

"Applicable Loading %" is a single configured gross-up applied to every Comprehensive quote for the product — the equivalent of the Medical engine's combined expense/contingency/profit loading, just collapsed to one number here.

03 — Discounts & the minimum-premium floor

NetGross, protected by a floor Implemented

Seven discount types subtract from Gross. If stacking all of them would push the premium below the scheme's minimum, the engine doesn't just clip the total — it reproduces the SP's own proportional shrink-back algorithm.

Discount	Trigger
No-Claims Discount (NCD)	Claim-free years
Scheme, falling back to User	Scheme code, or the individual user if the scheme has none
Loyalty (LD)	Caller-supplied eligibility flag
Driver	Caller-declared: a female driver exists on the policy
Promo	Caller-supplied percentage
Other	Caller-supplied percentage
Entity	Caller-supplied percentage

Several of these — Loyalty, Driver, Promo, Other, Entity — are trusted from the request rather than computed from a lookup the way the SP does it (the SP re-derives Loyalty from an actual prior-policy history check, and aggregator "Other" discounts from an aggregator-specific master table). This is fine as long as every calling channel is independently computing the correct value before it calls the engine — worth confirming with each channel team.

Driver Age top-up

A further loading applies against (Gross − NCD − Loyalty) for young/inexperienced drivers, netted against whatever Insured-Age loading was already applied in §2 so the same risk factor isn't charged twice:

Driver Age top-up

Raw Amount = (Gross − NCD Disc Amt − Loyalty Disc Amt) × Driver-Age Loading % Driver Age Amt = MAX( Raw Amount − Insured-Age Loading Amt already applied, 0 )

Minimum-premium floor — the reverse calculation

If NetGross would fall below the cached minimum premium for this Product / Vehicle Group / Region / Claim-Free-Years combination, the engine doesn't simply raise the price back up. It first checks which discount types are marked non-adjustable for this scheme, then shrinks only the adjustable ones proportionally until the floor is exactly met:

Reverse-calculation (matches the SP's own worked comment, verbatim)

If (Gross − Non-Adjustable Discount Amt) still clears the floor: Max Adjustable Disc Amt = (Gross − Non-Adjustable Disc Amt) − Minimum Premium Adjustment Ratio = Max Adjustable Disc Amt ÷ Total Adjustable Disc % → every adjustable discount % is scaled down by this ratio If even shrinking every adjustable discount to zero isn't enough: Gross += ( Minimum Premium ÷ (100 − Total Disc %) × 100 ) − Gross

This is one of the more intricate pieces of the SP, and it's been ported faithfully — the C# even carries the SP's own illustrative comment forward: 800 (Gross) − 450 (Min Premium) = 350 ÷ (20% + 10% + 5%) = 10.

04 — Additional Covers

Optional add-on covers Implemented

Every optional cover a customer can attach to a Comprehensive policy is now priced, checked for eligibility, loaded, and floored — exactly like the Basic Premium above but run a second time per cover, and returned alongside it in the same response.

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flowchart TD
    A1["Customer selects one or more Additional Covers"]
    A2["Eligibility filter
Make · Model · Vehicle-Age · Deductible-band · Business-Type"]
    A3["Rate lookup, per cover
Fixed amount / per-seat  —or—  rated by Region×BodyType×Nationality×
VehicleGroup×Usage×Deductible×InsuredAge×ManufactureYear"]
    A4["Re-run applicable loadings
(cover-specific subset of the same 13-factor chain)"]
    A5["Cover's own minimum premium, then VAT"]
    A6["= price for this cover"]
    A1 --> A2 --> A3 --> A4 --> A5 --> A6

What's priced, for Comprehensive

Cover	Pricing shape
Personal Accident — Driver	Rated per policy, own loading chain
Personal Accident — Passengers	Rated per seat (seating capacity × rate)
Zero Depreciation — Total Loss	% of Gross, vehicle-age gated
Zero Depreciation — Partial Loss	% of Gross, vehicle-age gated
Admin Fee and similar Fixed-rate covers	Flat fee per policy

Excluded by design: Geographical Extension covers (GCC/Bahrain/Egypt) and Replacement Vehicle — see the callout below for why.

Why this was more than "one more lookup table"

Three things made this a second pipeline rather than a quick add — all three are now handled:

Complication	How it's handled
Two pricing mechanisms	Some covers are a flat/per-seat "Fixed" rate; others are "Applicable at Cover level" — rated from an 8-dimension lookup table (region, body type, nationality, vehicle group, usage, deductible band, insured-age band, manufacture-year band). Both are cached and priced.
Per-vehicle eligibility rules	A separate whitelist table can restrict specific covers to specific Make/Model/Vehicle-Age/Deductible-band/Business-Type combinations — checked before a non-mandatory cover is offered.
The loading chain runs again	Each cover has its own data-driven map of which of the 13 loadings actually apply to it. The engine reuses the percentages already computed for the Basic Premium rather than re-querying — verified this map is currently empty for all Motor Comp products, so it's a correct no-op today.

Deliberately excluded, matching what production's live quote flow actually exercises (not what it theoretically supports): geographic-extension covers (Bahrain/Egypt/GCC/Other) and Replacement Cover — the reference SP always calls its additional-covers logic with no geographic-extension period selected, and its own Replacement Cover block is commented out in production. Sourced via 6 new stored procedures added to Acig_Limra_Db, following the same _RateEngine naming convention as the 8 already wired into MastersCache.

05 — Other known differences

Found while reviewing the SP Mixed

Additional Covers and VAT (§4, and the reference table below) are now closed. Comparing the engine line-by-line against the production SP surfaced five more differences — none as large, but worth a deliberate decision before or shortly after go-live.

Gap	Direction of error	Notes
Comprehensive premium CAP	Overstated (if activated)	Ceiling on Basic Premium by make/model/region/etc. Currently zero active rows in production — dormant, but live code in the SP.
Minimum-premium keying	Understated (edge cases)	Engine keys on Product/Vehicle-Group/Region/Claim-Years only; the SP also keys on Policy Type, Make, Model, Nationality, Manufacture Year, Repair Type.
Cross-Sell & Multi-Vehicle Discount	Overstated (discount withheld)	Both require a live per-customer "how many existing policies" lookup — structurally in tension with a pure in-memory cache. See `Project Details.md` §5.4 for options.
Motor Scheme Discount cap	Understated	A per-scheme ceiling on total stacked discount % is not enforced — a customer stacking several discounts could be quoted below what the scheme actually allows.
Region resolution	Could pick wrong tariff row	The SP's algorithm is materially richer (aggregator vs. non-aggregator branches, majority-vote across three region codes); the engine only handles the single-duplicate case.

Full detail, verbatim SQL references, and a phased remediation plan for each of these live in Project Details.md.

06 — Worked example

Basic Premium, start to finish

Illustrative figures at realistic Saudi Comprehensive magnitude — not real master data. Shown here is the Basic Premium chain through VAT; Additional Covers are priced separately per eligible cover and returned alongside this total (see §4).

Private car · Sum Insured 90,000 SAR · 5 claim-free years · Agency repair

Tariff Rate         = 6.24% of Sum Insured  →  90,000 × 6.24 / 100        = 5,616.00
TPL-floor premium   = 1,180 × 1.05 (min-premium config)                   =  1,239.00
Tariff Min Premium                                                        =  4,200.00
Basic Premium = MAX(5,616.00, 1,239.00, 4,200.00)                         =  5,616.00

Loadings on Basic Premium (5,616.00):
  Marital Status  +8%  →  449.28        Insured Age    +5%  →  280.80
  Repair Type    +11%  →  617.76        Region          +3%  →  168.48
  Deductible      +4%  →  224.64        NCD (loading)   -2%  → -112.32
  (all other loadings 0% for this profile)
Σ Loadings                                                                =  1,628.64

NRP = 5,616.00 + 1,628.64                                                 =  7,244.64
Applicable Loading % = 12%
Gross = 7,244.64 ÷ (100 − 12) × 100                                       =  8,232.55

Discounts on Gross (8,232.55):
  NCD Discount   -20%  → -1,646.51      Scheme Discount  -5%  →  -411.63
NetGross = 8,232.55 − 1,646.51 − 411.63                                   =  6,174.41

Minimum-Premium check: floor for this Product/Group/Region/NCD = 5,900.00
NetGross (6,174.41) already clears the floor → no reverse-calculation needed

VAT (flat 15%) = 6,174.41 × 15%                                           =    926.16
Final Basic Premium incl. VAT                                             =  7,100.57

07 — Reference

Formula reference

Stage	Formula	Status
Basic Premium	MAX(Rate × SI ÷ 100, TPL-floor × (1+MinCfg%), Tariff Min Premium)	Live
NRP	Basic Premium + Σ(13 loadings) + Accident Loading	Live
Gross	NRP ÷ (100 − Applicable Loading %) × 100	Live
NetGross	Gross − (NCD + Scheme/User + Loyalty + Driver + Promo + Other + Entity)	Live
Driver Age top-up	MAX((Gross−NCD−LD) × DriverAge% − InsAgeLoadingAmt, 0)	Live
Minimum-premium floor	Shrink adjustable discounts proportionally, else gross back up	Live
VAT	NetGross × VAT% (flat 15% today)	Live
Comprehensive CAP	MIN(Basic Premium, CAP amount or % of SI)	Missing (dormant in prod)
Additional Covers	Per-cover: eligibility → rate → loadings → min premium → VAT	Live
Cross-Sell / Multi-Vehicle Discount	Needs live per-customer existing-policy lookup	Missing
Motor Scheme Discount cap	Clip total stacked discount % to the scheme's ceiling	Missing

Reflects GIRateEngine/BAL/PremiumCalculation.cs as of 2026-07-30, verified line-by-line against the live SPGI_ACIG_GetPremium_Comp_Tameeni stored procedure and its supporting tables in Acig_Limra_Db. Worked-example figures are illustrative, not real master data. For the full gap analysis, security/operational findings, and a phased go-live plan, see Project Details.md in this repository.