diff --git a/src/components/forms/custom-form-builder.tsx b/src/components/forms/custom-form-builder.tsx
index af80017..14f90f6 100644
--- a/src/components/forms/custom-form-builder.tsx
+++ b/src/components/forms/custom-form-builder.tsx
@@ -1130,6 +1130,12 @@ export function CustomFormBuilder() {
               <div>
                 <Label className="text-xs uppercase tracking-wider text-muted-foreground">Variables</Label>
                 <p className="text-xs text-muted-foreground mt-1">Click to insert at cursor.</p>
+                <p className="text-[11px] text-muted-foreground mt-1 leading-snug">
+                  Control case with <code className="font-mono">|upper</code>,{" "}
+                  <code className="font-mono">|lower</code>, <code className="font-mono">|title</code>, or{" "}
+                  <code className="font-mono">|sentence</code>. Example:{" "}
+                  <code className="font-mono">{`{{ownerName|upper}}`}</code>
+                </p>
               </div>
               <div className="relative">
                 <Search className="absolute left-2.5 top-1/2 -translate-y-1/2 h-3.5 w-3.5 text-muted-foreground" />
diff --git a/src/lib/forms-shared.ts b/src/lib/forms-shared.ts
index 61174a5..930bd46 100644
--- a/src/lib/forms-shared.ts
+++ b/src/lib/forms-shared.ts
@@ -134,6 +134,47 @@ export async function fetchCustomFieldDefs(): Promise<CustomFieldVar[]> {
   return (data ?? []) as CustomFieldVar[];
 }
 
+// Case modifiers usable in templates as {{var|modifier}}.
+// Supported: upper, lower, title, sentence, capitalize (alias for sentence).
+export type CaseModifier = "upper" | "lower" | "title" | "sentence" | "capitalize";
+
+export function applyCase(value: string, modifier?: string | null): string {
+  if (!value || !modifier) return value ?? "";
+  const m = modifier.toLowerCase().trim();
+  switch (m) {
+    case "upper":
+      return value.toUpperCase();
+    case "lower":
+      return value.toLowerCase();
+    case "title":
+      // Capitalize each word; preserve internal punctuation/whitespace.
+      return value.toLowerCase().replace(/\b([a-z\u00C0-\u024F])/g, (c) => c.toUpperCase());
+    case "sentence":
+    case "capitalize": {
+      // Lowercase the whole string, then capitalize the first letter of each sentence.
+      const lower = value.toLowerCase();
+      return lower.replace(/(^\s*[a-z\u00C0-\u024F])|([.!?]\s+[a-z\u00C0-\u024F])/g, (s) =>
+        s.toUpperCase(),
+      );
+    }
+    default:
+      return value;
+  }
+}
+
+// Replace any occurrence of {{name}} or {{name|modifier}} using the provided lookup.
+function replaceWithModifier(
+  body: string,
+  pattern: RegExp,
+  resolver: (name: string) => string | undefined,
+): string {
+  return body.replace(pattern, (_match, rawName: string, _pipe: string | undefined, mod: string | undefined) => {
+    const value = resolver(rawName.trim());
+    if (value == null) return "";
+    return applyCase(value, mod);
+  });
+}
+
 export function applyVariables(
   body: string,
   ctx: {
@@ -145,32 +186,40 @@ export function applyVariables(
   },
 ): string {
   const today = format(new Date(), "MMMM d, yyyy");
-  const replacements: Record<string, string> = {
-    "{{clientName}}": ctx.client?.name ?? "",
-    "{{ownerName}}": ownerFullName(ctx.homeowner),
-    "{{propertyAddress}}": ctx.homeowner?.address ?? "",
-    "{{unitNumber}}": ctx.homeowner?.unit_number ?? "",
-    "{{accountNumber}}": ctx.homeowner?.unit_number ?? "",
-    "{{balance}}": (ctx.homeowner?.opening_balance ?? 0).toFixed(2),
-    "{{currentDate}}": today,
-    "{{firmName}}": ctx.firmName ?? "",
+  const systemValues: Record<string, string> = {
+    clientName: ctx.client?.name ?? "",
+    ownerName: ownerFullName(ctx.homeowner),
+    propertyAddress: ctx.homeowner?.address ?? "",
+    unitNumber: ctx.homeowner?.unit_number ?? "",
+    accountNumber: ctx.homeowner?.unit_number ?? "",
+    balance: (ctx.homeowner?.opening_balance ?? 0).toFixed(2),
+    currentDate: today,
+    firmName: ctx.firmName ?? "",
   };
+
   let out = body;
-  for (const [k, v] of Object.entries(replacements)) {
-    out = out.split(k).join(v);
-  }
-  // Custom case-field variables like {{custom.mortgage_holder}}
-  if (ctx.customValues) {
-    for (const [k, v] of Object.entries(ctx.customValues)) {
-      out = out.split(`{{custom.${k}}}`).join(v ?? "");
-    }
-  }
-  // Per-form fillable fields like {{field.tenant_name}}
-  if (ctx.fieldValues) {
-    for (const [k, v] of Object.entries(ctx.fieldValues)) {
-      out = out.split(`{{field.${k}}}`).join(v ?? "");
-    }
-  }
+
+  // System variables: {{name}} or {{name|modifier}}
+  out = replaceWithModifier(
+    out,
+    /\{\{\s*([a-zA-Z][a-zA-Z0-9_]*)\s*(\|\s*([a-zA-Z]+)\s*)?\}\}/g,
+    (name) => systemValues[name],
+  );
+
+  // Custom case-field variables: {{custom.key}} or {{custom.key|modifier}}
+  out = replaceWithModifier(
+    out,
+    /\{\{\s*custom\.([a-zA-Z0-9_]+)\s*(\|\s*([a-zA-Z]+)\s*)?\}\}/g,
+    (name) => ctx.customValues?.[name],
+  );
+
+  // Per-form fillable fields: {{field.key}} or {{field.key|modifier}}
+  out = replaceWithModifier(
+    out,
+    /\{\{\s*field\.([a-zA-Z0-9_]+)\s*(\|\s*([a-zA-Z]+)\s*)?\}\}/g,
+    (name) => ctx.fieldValues?.[name],
+  );
+
   return out;
 }