feat: Social Security deduction component

Employee's Social Security Fund contribution (Sec. 33): 5% of wages,
wages taken as at least 1,650 and at most 17,500 a month (2026-2028
ceiling), fractions of a baht rounded half up. Computed from the Basic
earning rather than `base` so a partial month is 5% of the wages
actually paid and the ceiling applies after proration. The contribution
is deductible from taxable income in full, so the component is
exempted_from_income_tax. Withheld amounts are held in "Social Security
Payable" (ประกันสังคมค้างจ่าย) until remitted.

Created once a Thai company exists (Company.on_update, install hooks,
scheduler, the setup_salary_components patch); the Salary Component
validate hook links every Thai company.

default_thai_company/payroll.py

@@ -24,6 +24,30 @@ INCOME_TAX_ACCOUNT = "Withholding Tax Payable (P.N.D.1)"
 DEDUCTION_ACCOUNT = "Salary Deductions"
 DEDUCTION_ACCOUNT_GROUPS = ("Current Liabilities",)
 
+# Employee's Social Security Fund contribution (Sec. 33): 5% of wages, wages
+# taken as at least 1,650 and at most 17,500 a month (2026-2028 ceiling; 20,000
+# from 2029), fractions of a baht rounded half up. Computed from the Basic
+# earning rather than `base` so a partial month is 5% of the wages actually paid
+# and the ceiling applies after proration, as the Social Security Office
+# assesses it. The contribution is deductible from taxable income in full, so
+# the component is exempted_from_income_tax; the "Social Security Fund"
+# exemption sub-category is for contributions not run through payroll here.
+# The employer's equal share is not an employee deduction and is left to the
+# accounts. Thai books carry the withheld amount as ประกันสังคมค้างจ่าย until
+# it is remitted by the 15th, so it gets its own liability.
+SOCIAL_SECURITY_COMPONENT = {
+	"doctype": "Salary Component",
+	"salary_component": "Social Security",
+	"salary_component_abbr": "SSO",
+	"type": "Deduction",
+	"description": "Social Security Fund contribution (Sec. 33 employee)",
+	"depends_on_payment_days": 0,
+	"exempted_from_income_tax": 1,
+	"condition": "B > 0",
+	"amount_based_on_formula": 1,
+	"formula": "int((1650 if B < 1650 else 17500 if B > 17500 else B) * 5 / 100 + 0.5)",
+}
+SOCIAL_SECURITY_ACCOUNT = "Social Security Payable"
 
 
 def hrms_installed():
@@ -35,6 +59,10 @@ def salary_component_account(company, component):
 		return get_or_create_account(company, EARNING_ACCOUNT, "Expense", "", EARNING_ACCOUNT_GROUPS)
 	if component.is_income_tax_component:
 		return get_or_create_account(company, INCOME_TAX_ACCOUNT, "Liability")
+	if component.salary_component == SOCIAL_SECURITY_COMPONENT["salary_component"]:
+		return get_or_create_account(
+			company, SOCIAL_SECURITY_ACCOUNT, "Liability", "", DEDUCTION_ACCOUNT_GROUPS
+		)
 	return get_or_create_account(company, DEDUCTION_ACCOUNT, "Liability", "", DEDUCTION_ACCOUNT_GROUPS)
 
 
@@ -62,6 +90,13 @@ def ensure_component_accounts(company):
 			component.save(ignore_permissions=True)
 
 
+def ensure_social_security_component():
+	"""Social Security deduction; the validate hook links every Thai company."""
+	if frappe.db.exists("Salary Component", SOCIAL_SECURITY_COMPONENT["salary_component"]):
+		return
+	frappe.get_doc(SOCIAL_SECURITY_COMPONENT).insert(ignore_permissions=True)
+
+
 def payroll_period_name(company, year):
 	abbr = frappe.get_cached_value("Company", company, "abbr")
 	return f"{year} - {abbr}"
@@ -88,21 +123,26 @@ def ensure_payroll_period(company, year):
 
 
 def setup_company(doc, method=None):
-	"""Company.on_update: this year's Payroll Period and the Salary Component
-	accounts for a Thai company."""
+	"""Company.on_update: this year's Payroll Period, the Social Security
+	component and the Salary Component accounts for a Thai company."""
 	if doc.country == "Thailand" and hrms_installed():
 		ensure_payroll_period(doc.name, getdate().year)
+		ensure_social_security_component()
 		ensure_component_accounts(doc.name)
 
 
 def setup_companies():
 	"""after_install, the daily scheduler, and the setup_salary_components
-	patch: this year's Payroll Period and the Salary Component accounts for
-	every Thai company. The scheduler rolls the Payroll Period over on 1 January."""
+	patch: this year's Payroll Period, the Social Security component and the
+	Salary Component accounts for every Thai company. The scheduler rolls the
+	Payroll Period over on 1 January."""
 	if not hrms_installed():
 		return
 	year = getdate().year
-	for company in thai_companies():
+	companies = thai_companies()
+	if companies:
+		ensure_social_security_component()
+	for company in companies:
 		ensure_payroll_period(company, year)
 		ensure_component_accounts(company)
 

default_thai_company/translations/th.csv

@@ -76,6 +76,9 @@ Page {0} of {1},หน้า {0} จาก {1}
 Withholding Tax Payable,ภาษีหัก ณ ที่จ่ายค้างจ่าย
 Withholding Tax Payable (P.N.D.1),ภาษีหัก ณ ที่จ่ายค้างจ่าย (ภ.ง.ด.1)
 Salary Deductions,รายการหักจากเงินเดือน
+Social Security,ประกันสังคม
+Social Security Payable,ประกันสังคมค้างจ่าย
+Social Security Fund contribution (Sec. 33 employee),เงินสมทบกองทุนประกันสังคม (ผู้ประกันตนมาตรา 33)
 Withholding Tax Receivable,ภาษีถูกหัก ณ ที่จ่าย
 Output VAT,ภาษีขาย
 Input VAT,ภาษีซื้อ