Accessory stamp duty and LCT

This page is the single source for how accessory GST-inclusive amounts are split for stamp duty (state/territory) and luxury car tax (LCT) (federal). The same rules apply to the public Calculate Government Charges API (optional accessory IDs), AccessoryGovernmentChargeInclusion in app/services/accessory_government_charge_inclusion.rb, and sales contract dutiable accessory lines.

Important: Rules are by type_for_government_charges on each accessory, not by product name. In the Dashboard, that field is Government charges type on the accessory record.

Blank or missing type (legacy data)

If type_for_government_charges is blank (NULL / unset in the database), the system treats that accessory as included in stamp duty everywhere (including WA) and included in LCT. That is softer than an explicit dealer_fitted_accessory in WA (which is excluded from stamp duty only once the type is set). Prefer setting the correct type on every accessory.

LCT (federal — same in every state and territory)

LCT does not vary by jurisdiction. Only type_for_government_charges matters.

Government charges type (`type_for_government_charges`)	Included in LCT dutiable total?
`extended_warranties`	Yes
`factory_option`	Yes
`dealer_fitted_accessory`	Yes
`insurance_product`	Yes
`service_plans`	No
`maintenance_plan`	No
Blank / unknown value	Yes (default)

Stamp duty (state and territory)

Stamp duty rules use a jurisdiction code (e.g. NSW, WA). Callers should pass the Australian state or territory abbreviation in upper case; the service normalises with .upcase.

Where every jurisdiction behaves the same

For these types, every state and territory (NSW, VIC, QLD, SA, WA, TAS, ACT, NT) uses the same answer: the accessory price is not counted toward the stamp-duty dutiable base.

Type	Stamp duty (all states and territories)
`extended_warranties`	Excluded
`insurance_product`	Excluded
`service_plans`	Excluded

The only state-specific rule: dealer-fitted accessories

Type	NSW, VIC, QLD, SA, TAS, ACT, NT	WA
`dealer_fitted_accessory`	Included	Excluded

So Western Australia is the only jurisdiction where dealer-fitted accessory amounts are kept out of the stamp-duty accessory split. LCT for those same lines still follows the federal table above (dealer-fitted remains in the LCT base).

Included in stamp duty in every state (including WA)

Type	Stamp duty
`factory_option`	Included
`maintenance_plan`	Included

(These types are not in the “excluded everywhere” list, and maintenance_plan is not treated as dealer-fitted, so WA does not strip them from stamp duty.)

Summary by jurisdiction (human-readable)

New South Wales, Victoria, Queensland, South Australia, Tasmania, Australian Capital Territory, Northern Territory
Stamp duty on accessories: exclude extended warranties, insurance products, and service plans; include factory options, maintenance plans, and dealer-fitted accessories.
Western Australia
Same as above, except dealer-fitted accessories are excluded from the stamp-duty portion (factory options and maintenance plans still count toward stamp duty where applicable).

Optional overrides (developers)

STAMP_DUTY_OVERRIDES_BY_JURISDICTION in AccessoryGovernmentChargeInclusion allows a per jurisdiction, per type override map. It is currently empty. If populated, those entries override all of the rules above for matching jurisdiction and type.

Official jurisdictional sources (dutiable value)

Revenue guidance extracts (ACT, NSW, QLD, TAS, WA, NT) and federal LCT links for context alongside these product rules: Government charges — dutiable value and accessories (Starlight; same path under starlight-docs/src/content/docs/guides/accessories/ in the repo).

Service: app/services/accessory_government_charge_inclusion.rb
Specs: spec/services/accessory_government_charge_inclusion_spec.rb
Accessories feature overview: docs/accessories/overview.md
Sales contract rules inventory: docs/sales_contract/business_rules_inventory.md

API consumers

Calculate Government Charges — OpenAPI reference on the docs site
Getting Started — authentication and API keys (calculate:government_charge permission is required for that endpoint)

This file is symlinked into Starlight at starlight-docs/src/content/docs/guides/government-charges/accessory-stamp-duty-and-lct.md so dev.dealerstudio.com.au stays in sync with the repository copy.