diff --git a/src/services/accounting-service.js b/src/services/accounting-service.js
index 39ccb18..423f27e 100644
--- a/src/services/accounting-service.js
+++ b/src/services/accounting-service.js
@@ -392,6 +392,8 @@ async function getTaxSummary({ startDate, endDate, accountingMethod = 'Accrual'
 
     const whereClause = `TxnDate >= '${startDate}' AND TxnDate <= '${endDate}'`;
     const agg = {};
+    let totalSales = 0;
+    let totalTaxable = 0;
 
     for (const entity of ['Invoice', 'SalesReceipt']) {
         try {
@@ -401,8 +403,14 @@ async function getTaxSummary({ startDate, endDate, accountingMethod = 'Accrual'
             const docs = data?.QueryResponse?.[entity] || [];
             for (const doc of docs) {
                 const taxDetail = doc.TxnTaxDetail;
+                const totalAmt = parseFloat(doc.TotalAmt) || 0;
+                const totalTax = taxDetail ? (parseFloat(taxDetail.TotalTax) || 0) : 0;
+                totalSales += (totalAmt - totalTax);
+
                 if (!taxDetail || !taxDetail.TaxLine) continue;
+
                 const taxLines = Array.isArray(taxDetail.TaxLine) ? taxDetail.TaxLine : [taxDetail.TaxLine];
+                let docTaxable = 0;
                 for (const line of taxLines) {
                     const detail = line.TaxLineDetail;
                     if (!detail || !detail.TaxRateRef) continue;
@@ -412,13 +420,16 @@ async function getTaxSummary({ startDate, endDate, accountingMethod = 'Accrual'
                     if (!agg[rateId]) agg[rateId] = { taxableSales: 0, taxCollected: 0 };
                     agg[rateId].taxableSales += taxable;
                     agg[rateId].taxCollected += collected;
+                    docTaxable = Math.max(docTaxable, taxable);
                 }
+                totalTaxable += docTaxable;
             }
         } catch (e) {
             console.error(`${entity} query failed:`, e.message);
         }
     }
 
+    const nontaxableSales = totalSales - totalTaxable;
     const rows = Object.entries(agg).map(([rateId, amounts]) => {
         const info = rateMap[rateId] || { name: `Tax Rate ${rateId}`, rateValue: 0 };
         const ratePct = info.rateValue.toFixed(3).replace(/0+$/, '').replace(/\.$/, '');
@@ -429,12 +440,16 @@ async function getTaxSummary({ startDate, endDate, accountingMethod = 'Accrual'
                     { value: info.name },
                     { value: '' },
                     { value: '' },
+                    { value: '' },
+                    { value: '' },
                     { value: `${ratePct}%` }
                 ]
             },
             Summary: {
                 ColData: [
                     { value: 'Total' },
+                    { value: totalSales.toFixed(2) },
+                    { value: nontaxableSales.toFixed(2) },
                     { value: amounts.taxableSales.toFixed(2) },
                     { value: amounts.taxCollected.toFixed(2) },
                     { value: `${ratePct}%` }
@@ -451,6 +466,27 @@ async function getTaxSummary({ startDate, endDate, accountingMethod = 'Accrual'
         return na.localeCompare(nb);
     });
 
+    const grandTaxCollected = Object.values(agg).reduce((s, a) => s + a.taxCollected, 0);
+    rows.push({
+        type: 'Section',
+        Header: {
+            ColData: [
+                { value: 'GRAND TOTAL' },
+                { value: '' }, { value: '' }, { value: '' }, { value: '' }, { value: '' }
+            ]
+        },
+        Summary: {
+            ColData: [
+                { value: 'Total' },
+                { value: totalSales.toFixed(2) },
+                { value: nontaxableSales.toFixed(2) },
+                { value: totalTaxable.toFixed(2) },
+                { value: grandTaxCollected.toFixed(2) },
+                { value: '' }
+            ]
+        }
+    });
+
     return {
         Header: {
             ReportName: 'Sales Tax Liability',
@@ -461,7 +497,9 @@ async function getTaxSummary({ startDate, endDate, accountingMethod = 'Accrual'
         Columns: {
             Column: [
                 { ColTitle: '', ColType: 'Text' },
-                { ColTitle: 'Taxable Sales', ColType: 'Money' },
+                { ColTitle: 'Total Sales', ColType: 'Money' },
+                { ColTitle: 'Nontaxable', ColType: 'Money' },
+                { ColTitle: 'Taxable', ColType: 'Money' },
                 { ColTitle: 'Tax Collected', ColType: 'Money' },
                 { ColTitle: 'Tax Rate', ColType: 'Percent' }
             ]