offer_vassalization_interaction_effect

offer_vassalization_interaction_effect = {
	create_title_and_vassal_change = {
		type = swear_fealty
		save_scope_as = change
	}
	scope:recipient = {
		change_liege = {
			liege = scope:puppet_or_actor
			change = scope:change
		}
		add_opinion = {
			modifier = became_vassal
			target = scope:puppet_or_actor
			opinion = 10
		}
	}
	resolve_title_and_vassal_change = scope:change

	# Special terms for feudal contracts
	scope:recipient = {
		if = {
			limit = {
				government_has_flag = government_is_feudal
			}
			if = {
				limit = { scope:high_obligations ?= yes }
				hidden_effect = {
					if = {
						limit = { top_liege != this } # To avoid errors during tooltip generation (prior to the contract being generated)
						vassal_contract_set_obligation_level = { type = feudal_government_taxes level = 3 }
						vassal_contract_set_obligation_level = { type = feudal_government_levies level = 3 }
					}
				}
				custom_tooltip = high_obligations_taxes
				custom_tooltip = high_obligations_levies
			}
			else_if = {
				limit = { scope:low_obligations ?= yes }
				hidden_effect = {
					if = {
						limit = { top_liege != this } # To avoid errors during tooltip generation (prior to the contract being generated)
						vassal_contract_set_obligation_level = { type = feudal_government_taxes level = 1 }
						vassal_contract_set_obligation_level = { type = feudal_government_levies level = 1 }
					}
				}
				custom_tooltip = low_obligations_taxes
				custom_tooltip = low_obligations_levies
			}
			else_if = {
				limit = { scope:religious_exemption ?= yes }
				hidden_effect = {
					if = {
						limit = { top_liege != this } # To avoid errors during tooltip generation (prior to the contract being generated)
						vassal_contract_set_obligation_level = { type = feudal_government_taxes level = 2 }
						vassal_contract_set_obligation_level = { type = feudal_government_levies level = 1 }
						vassal_contract_set_obligation_level = { type = religious_rights level = 1 }
					}
				}
				custom_tooltip = normal_obligations_taxes
				custom_tooltip = low_obligations_levies
				custom_tooltip = religious_protection_tt
			}
			else = {
				hidden_effect = {
					if = {
						limit = { top_liege != this } # To avoid errors during tooltip generation (prior to the contract being generated)
						vassal_contract_set_obligation_level = { type = feudal_government_taxes level = 2 }
						vassal_contract_set_obligation_level = { type = feudal_government_levies level = 2 }
					}
				}
				custom_tooltip = normal_obligations_taxes
				custom_tooltip = normal_obligations_levies
			}
		}
		else_if = {
			limit = {
				government_has_flag = government_is_clan
				scope:religious_exemption_clan ?= yes
			}
			hidden_effect = {
				if = {
					limit = { top_liege != this } # To avoid errors during tooltip generation (prior to the contract being generated)
					vassal_contract_set_obligation_level = { type = religious_rights level = 1 }
				}
			}
			custom_tooltip = religious_protection_tt
		}
	}

	# Struggle catalysts.
	hidden_effect = {
		fp3_struggle_apply_independent_vassalage_catalyst_effect = {
			NEW_LIEGE = scope:puppet_or_actor
			NEW_VASSAL = scope:recipient
		}
	}
}

As written in game/common/scripted_effects/00_interaction_effects.txt.