diff --git a/static/js/cit_calc.js b/static/js/cit_calc.js
new file mode 100644
index 0000000..b18503e
--- /dev/null
+++ b/static/js/cit_calc.js
@@ -0,0 +1,89 @@
+document.addEventListener("DOMContentLoaded", function () {
+
+ const fields = [
+ "gross_total_income", "disallowance_14a", "disallowance_37",
+ "deduction_80ia_business", "deduction_sec37_disallowance", "deduction_80g",
+ "net_taxable_income", "tax_30_percent", "tax_book_profit_18_5",
+ "tax_payable", "surcharge_12", "edu_cess_3", "total_tax_payable",
+ "mat_credit", "interest_234c", "total_tax",
+ "advance_tax", "tds", "tcs", "tax_on_assessment", "refund"
+ ];
+
+ function getVal(id) {
+ let el = document.getElementsByName(id)[0];
+ return el ? parseFloat(el.value) || 0 : 0;
+ }
+
+ function setVal(id, value) {
+ let el = document.getElementsByName(id)[0];
+ if (el) el.value = Number(value).toFixed(2);
+ }
+
+ function calculate() {
+
+ // Base values
+ let gross_total_income = getVal("gross_total_income");
+ let disallowance_14a = getVal("disallowance_14a");
+ let disallowance_37 = getVal("disallowance_37");
+
+ // Deductions
+ let d80_business = getVal("deduction_80ia_business");
+ let deduction_sec37 = getVal("deduction_sec37_disallowance");
+ let deduction_80g = getVal("deduction_80g");
+
+ // Net Taxable Income
+ let net_taxable_income =
+ (gross_total_income + disallowance_14a + disallowance_37)
+ - (d80_business + deduction_sec37)
+ - deduction_80g;
+
+ setVal("net_taxable_income", net_taxable_income);
+
+ // 30% tax
+ let tax_30_percent = net_taxable_income * 0.30;
+ setVal("tax_30_percent", tax_30_percent);
+
+ // Book profit tax (user input)
+ let tax_payable = getVal("tax_book_profit_18_5");
+ setVal("tax_payable", tax_payable);
+
+ // Surcharge 12%
+ let surcharge_12 = tax_payable * 0.12;
+ setVal("surcharge_12", surcharge_12);
+
+ // Education Cess 3%
+ let edu_cess_3 = (tax_payable + surcharge_12) * 0.03;
+ setVal("edu_cess_3", edu_cess_3);
+
+ // Total Tax Payable
+ let total_tax_payable = tax_payable + surcharge_12 + edu_cess_3;
+ setVal("total_tax_payable", total_tax_payable);
+
+ // MAT + Interest
+ let mat_credit = getVal("mat_credit");
+ let interest_234c = getVal("interest_234c");
+
+ // Total Tax
+ let total_tax = total_tax_payable + mat_credit + interest_234c;
+ setVal("total_tax", total_tax);
+
+ // Assessment → Advance Tax + TDS + TCS
+ let advance_tax = getVal("advance_tax");
+ let tds = getVal("tds");
+ let tcs = getVal("tcs");
+
+ let tax_on_assessment = advance_tax + tds + tcs;
+ setVal("tax_on_assessment", tax_on_assessment);
+
+ // Refund (or payable)
+ let refund = total_tax - tax_on_assessment;
+ setVal("refund", refund);
+ }
+
+ // Attach listeners
+ fields.forEach(id => {
+ let el = document.getElementsByName(id)[0];
+ if (el) el.addEventListener("input", calculate);
+ });
+
+});
diff --git a/templates/add_cit.html b/templates/add_cit.html
index 61d748a..a17fadc 100644
--- a/templates/add_cit.html
+++ b/templates/add_cit.html
@@ -4,6 +4,7 @@
CIT Form Entry
+