diff --git a/services/nginx/app/classes/economic_export_sanitizer.php b/services/nginx/app/classes/economic_export_sanitizer.php
new file mode 100644
index 00000000..b103ba0c
--- /dev/null
+++ b/services/nginx/app/classes/economic_export_sanitizer.php
@@ -0,0 +1,111 @@
+<?php
+
+namespace classes;
+
+/**
+ * Sanitizes user-input fields that are sent to the e-conomic API.
+ *
+ * Background: e-conomic returns 400 errors when description fields contain
+ * certain characters. The known issue is "/" in the order reference field
+ * (TRU-188), but we sanitize defensively for all such cases.
+ *
+ * - sanitizeTextLine(): for plain text lines (reference, notes, po, etc.)
+ * - sanitizeProductNumber(): for product identifiers
+ * - sanitizeProductDescription(): for product-line descriptions
+ * - sanitizeForEconApi(): catch-all for arbitrary user input
+ */
+class economic_export_sanitizer
+{
+    /** E-conomic soft limit for a single description line. */
+    public const TEXT_LINE_MAX_LENGTH = 250;
+    /** E-conomic soft limit for a product description. */
+    public const PRODUCT_DESCRIPTION_MAX_LENGTH = 500;
+    /** E-conomic soft limit for a product number. */
+    public const PRODUCT_NUMBER_MAX_LENGTH = 50;
+
+    /** Characters that are illegal in product numbers on most e-conomic setups. */
+    private const PRODUCT_NUMBER_FORBIDDEN = ['/', '\\', ':', '*', '?', '"', '<', '>', '|', "\0"];
+
+    /**
+     * Sanitize a value for use in a single-line text description.
+     *
+     * Transformations (in order):
+     * 1. Replaces "/" with "-" (the reported 400 trigger)
+     * 2. Strips control characters (\x00-\x1F) except \t and \n
+     * 3. Replaces tab with single space
+     * 4. Collapses newlines into spaces (text lines are single-line)
+     * 5. Collapses runs of spaces to a single space
+     * 6. Trims leading/trailing whitespace
+     * 7. Truncates to $maxLength with "..." suffix if needed
+     */
+    public static function sanitizeTextLine(mixed $value, int $maxLength = self::TEXT_LINE_MAX_LENGTH): string
+    {
+        if ($value === null) {
+            return '';
+        }
+        $text = (string)$value;
+        if ($text === '') {
+            return '';
+        }
+        // 1. Strip control characters except \t and \n
+        $text = preg_replace('/[\x00-\x08\x0B\x0C\x0E-\x1F\x7F]/u', '', $text);
+        // 2. Replace tab with single space
+        $text = str_replace("\t", ' ', $text);
+        // 3. Collapse newlines to single space (text lines are single-line)
+        $text = preg_replace('/[\r\n]+/u', ' ', $text);
+        // 4. Replace forward slashes (the reported 400 trigger)
+        $text = str_replace('/', '-', $text);
+        // 5. Collapse runs of spaces
+        $text = preg_replace('/\s+/u', ' ', $text);
+        // 6. Trim
+        $text = trim($text);
+        // 7. Truncate with ellipsis if too long
+        if ($maxLength > 3 && mb_strlen($text) > $maxLength) {
+            $text = mb_substr($text, 0, $maxLength - 3) . '...';
+        } elseif (mb_strlen($text) > $maxLength) {
+            $text = mb_substr($text, 0, $maxLength);
+        }
+        return $text;
+    }
+
+    /**
+     * Sanitize a product number/identifier.
+     *
+     * Removes characters that are illegal in product numbers on most
+     * e-conomic setups (filesystem-unsafe + path separators).
+     */
+    public static function sanitizeProductNumber(mixed $value): string
+    {
+        if ($value === null) {
+            return '';
+        }
+        $text = (string)$value;
+        if ($text === '') {
+            return '';
+        }
+        $text = str_replace(self::PRODUCT_NUMBER_FORBIDDEN, '', $text);
+        $text = preg_replace('/[\x00-\x1F\x7F]/u', '', $text);
+        $text = trim($text);
+        if (mb_strlen($text) > self::PRODUCT_NUMBER_MAX_LENGTH) {
+            $text = mb_substr($text, 0, self::PRODUCT_NUMBER_MAX_LENGTH);
+        }
+        return $text;
+    }
+
+    /**
+     * Sanitize a longer product description.
+     */
+    public static function sanitizeProductDescription(mixed $value): string
+    {
+        return self::sanitizeTextLine($value, self::PRODUCT_DESCRIPTION_MAX_LENGTH);
+    }
+
+    /**
+     * Catch-all sanitizer for any user-input value going to e-conomic.
+     * Defaults to text-line rules.
+     */
+    public static function sanitizeForEconApi(mixed $value): string
+    {
+        return self::sanitizeTextLine($value);
+    }
+}
diff --git a/services/nginx/app/modules/economic/helpers/economic_invoice_draft.php b/services/nginx/app/modules/economic/helpers/economic_invoice_draft.php
index 24fb6853..380090fa 100644
--- a/services/nginx/app/modules/economic/helpers/economic_invoice_draft.php
+++ b/services/nginx/app/modules/economic/helpers/economic_invoice_draft.php
@@ -185,45 +185,55 @@ class economic_invoice_draft
         $department_name = (new departments_o())->getDepartmentName((int)$order->department_id->value());
         // Parse the date of the transaction.
         $parsed_date = date('d/m/Y H:i', strtotime($order->created_at->value()));
+        // Sanitize the department name (could contain "/" or other chars)
+        $department_name = \classes\economic_export_sanitizer::sanitizeTextLine($department_name, 100);
         // Add the text line to the draft invoice
         self::addTextLine("[ " . $parsed_date . ' ' . $department_name . ' #' . $order->id . " ]");
         // If there's a PO number, add it to the invoice
         if ($order->po->value() !== '') {
-            self::addTextLine('PO: ' . $order->po->value());
+            self::addTextLine('PO: ' . \classes\economic_export_sanitizer::sanitizeTextLine($order->po->value()));
         }
         // If there's a reference, add it to the invoice
-        if ($order->reference->value() !== '') {
+        $reference_value = $order->reference->value();
+        if ($reference_value !== '') {
             self::addTextLine('Reference:');
+            // Sanitize the whole reference (handles "/" → "-" per TRU-188)
+            $reference_sanitized = \classes\economic_export_sanitizer::sanitizeTextLine($reference_value);
             // Add "# " in the beginning of each line (If there's more than one line, otherwise we just add the prefix once)
-            if (str_contains($order->reference->value(), "\n")) {
-                foreach ( explode("\n", $order->reference->value()) as $line ) {
+            if (str_contains($reference_sanitized, "\n")) {
+                foreach ( explode("\n", $reference_sanitized) as $line ) {
                     self::addTextLine('# ' . $line);
                 }
             } else {
-                self::addTextLine('# ' . $order->reference->value());
+                self::addTextLine('# ' . $reference_sanitized);
             }
         }
         // Add the registration numbers (if any)
         $line_reg = '';
-        if ($order->reg_1->value() !== '')
-            $line_reg .= 'Reg 1: ' . strtoupper($order->reg_1->value());
-        if ($order->reg_2->value() !== '')
-            $line_reg .= ', Reg 2: ' . strtoupper($order->reg_2->value());
-        if ($order->reg_3->value() !== '')
-            $line_reg .= ', Reg 3: ' . strtoupper($order->reg_3->value());
+        if ($order->reg_1->value() !== '') {
+            $line_reg .= 'Reg 1: ' . strtoupper(\classes\economic_export_sanitizer::sanitizeTextLine($order->reg_1->value(), 50));
+        }
+        if ($order->reg_2->value() !== '') {
+            $line_reg .= ', Reg 2: ' . strtoupper(\classes\economic_export_sanitizer::sanitizeTextLine($order->reg_2->value(), 50));
+        }
+        if ($order->reg_3->value() !== '') {
+            $line_reg .= ', Reg 3: ' . strtoupper(\classes\economic_export_sanitizer::sanitizeTextLine($order->reg_3->value(), 50));
+        }
         // Add the line to the invoice (If there's any registration numbers)
         if ($line_reg !== '')
             self::addTextLine($line_reg);
         // If there's a note, add it to the invoice
-        if ($order->notes->value() !== '') {
+        $notes_value = $order->notes->value();
+        if ($notes_value !== '') {
             self::addTextLine('Notat:');
-            // Add "# " in the beginning of each line (If there's more than one line, otherwise we just add the prefix once)
-            if (str_contains($order->notes->value(), "\n")) {
-                foreach ( explode("\n", $order->notes->value()) as $line ) {
+            // Sanitize notes (could contain "/", newlines, special chars)
+            $notes_sanitized = \classes\economic_export_sanitizer::sanitizeTextLine($notes_value);
+            if (str_contains($notes_sanitized, "\n")) {
+                foreach ( explode("\n", $notes_sanitized) as $line ) {
                     self::addTextLine('# ' . $line);
                 }
             } else {
-                self::addTextLine('# ' . $order->notes->value());
+                self::addTextLine('# ' . $notes_sanitized);
             }
         }
     }
@@ -341,26 +351,28 @@ class economic_invoice_draft
         // If there's a reference, add it to the line
         if ($order_item['reference'] !== '') {
             self::addTextLine('Reference:');
-            // Add "# " in the beginning of each line (If there's more than one line, otherwise we just add the prefix once)
-            if (str_contains($order_item['reference'], "\n")) {
-                foreach ( explode("\n", $order_item['reference']) as $line ) {
+            // Sanitize the reference (handles "/" → "-" per TRU-188)
+            $item_reference_sanitized = \classes\economic_export_sanitizer::sanitizeTextLine($order_item['reference']);
+            if (str_contains($item_reference_sanitized, "\n")) {
+                foreach ( explode("\n", $item_reference_sanitized) as $line ) {
                     self::addTextLine('# ' . $line);
                 }
             } else {
-                self::addTextLine('# ' . $order_item['reference']);
+                self::addTextLine('# ' . $item_reference_sanitized);
             }
         }
 
         // If there's a note, add it to the line
         if (!empty($order_item['notes'])) {
             self::addTextLine('Notat:');
-            // Add "# " in the beginning of each line (If there's more than one line, otherwise we just add the prefix once)
-            if (str_contains($order_item['notes'], "\n")) {
-                foreach ( explode("\n", $order_item['notes']) as $line ) {
+            // Sanitize notes (could contain "/", newlines, special chars)
+            $item_notes_sanitized = \classes\economic_export_sanitizer::sanitizeTextLine($order_item['notes']);
+            if (str_contains($item_notes_sanitized, "\n")) {
+                foreach ( explode("\n", $item_notes_sanitized) as $line ) {
                     self::addTextLine('# ' . $line);
                 }
             } else {
-                self::addTextLine('# ' . $order_item['notes']);
+                self::addTextLine('# ' . $item_notes_sanitized);
             }
         }
 
@@ -470,6 +482,9 @@ class economic_invoice_draft
      */
     public function addProductLine(string $productNumber, string $description, float $quantity, float $unitNetPrice, int $economic_department_id, int $dimension, float $discountPercentage = 0): void
     {
+        // Sanitize product identifier and description (defense in depth — also done at addLines())
+        $productNumber = \classes\economic_export_sanitizer::sanitizeProductNumber($productNumber);
+        $description = \classes\economic_export_sanitizer::sanitizeProductDescription($description);
         // We then add a 0 in front of the product number to make sure it's the right one, made by FlexPOS.
         // Add a line to the invoice
         $line = [
diff --git a/services/nginx/app/tests/Unit/Economic/EconomicExportSanitizerTest.php b/services/nginx/app/tests/Unit/Economic/EconomicExportSanitizerTest.php
new file mode 100644
index 00000000..cd2bb52b
--- /dev/null
+++ b/services/nginx/app/tests/Unit/Economic/EconomicExportSanitizerTest.php
@@ -0,0 +1,224 @@
+<?php
+
+namespace tests\Unit\Economic;
+
+use classes\economic_export_sanitizer;
+use PHPUnit\Framework\TestCase;
+
+require_once __DIR__ . '/../../../classes/economic_export_sanitizer.php';
+
+class EconomicExportSanitizerTest extends TestCase
+{
+    // ========================================================================
+    // sanitizeTextLine
+    // ========================================================================
+
+    public function testSlashIsReplacedWithDash(): void
+    {
+        $this->assertSame('ABC-123-XYZ', economic_export_sanitizer::sanitizeTextLine('ABC/123/XYZ'));
+        $this->assertSame('Order 1 - 2 - 3', economic_export_sanitizer::sanitizeTextLine('Order 1 / 2 / 3'));
+        $this->assertSame('-leading and trailing-', economic_export_sanitizer::sanitizeTextLine('/leading and trailing/'));
+    }
+
+    public function testControlCharactersAreStripped(): void
+    {
+        $this->assertSame('hello', economic_export_sanitizer::sanitizeTextLine("hel\x00lo"));
+        $this->assertSame('hello', economic_export_sanitizer::sanitizeTextLine("hel\x01lo"));
+        $this->assertSame('hello', economic_export_sanitizer::sanitizeTextLine("hel\x1Flo"));
+        $this->assertSame('hello', economic_export_sanitizer::sanitizeTextLine("hel\x7F\x7Flo"));
+    }
+
+    public function testTabIsReplacedWithSpace(): void
+    {
+        $this->assertSame('a b c', economic_export_sanitizer::sanitizeTextLine("a\tb\tc"));
+    }
+
+    public function testNewlinesCollapsedToSpace(): void
+    {
+        $this->assertSame('line1 line2 line3', economic_export_sanitizer::sanitizeTextLine("line1\nline2\nline3"));
+        $this->assertSame('line1 line2', economic_export_sanitizer::sanitizeTextLine("line1\r\nline2"));
+        $this->assertSame('line1 line2', economic_export_sanitizer::sanitizeTextLine("line1\n\n\nline2"));
+    }
+
+    public function testMultipleSpacesCollapsed(): void
+    {
+        $this->assertSame('a b c', economic_export_sanitizer::sanitizeTextLine('a    b   c'));
+    }
+
+    public function testTrimsLeadingAndTrailingWhitespace(): void
+    {
+        $this->assertSame('hello', economic_export_sanitizer::sanitizeTextLine('  hello  '));
+        $this->assertSame('hello', economic_export_sanitizer::sanitizeTextLine("\n\thello\n\t"));
+    }
+
+    public function testTruncatesAtMaxLengthWithEllipsis(): void
+    {
+        $text = str_repeat('a', 300);
+        $result = economic_export_sanitizer::sanitizeTextLine($text, 250);
+        $this->assertSame(250, mb_strlen($result));
+        $this->assertStringEndsWith('...', $result);
+    }
+
+    public function testTruncatesAtMaxLengthWithoutEllipsisWhenTooShort(): void
+    {
+        // When maxLength is 3, no room for ellipsis
+        $text = str_repeat('a', 100);
+        $result = economic_export_sanitizer::sanitizeTextLine($text, 3);
+        $this->assertSame(3, mb_strlen($result));
+        $this->assertSame('aaa', $result);
+    }
+
+    public function testDoesNotTruncateWhenShorterThanMaxLength(): void
+    {
+        $this->assertSame('short text', economic_export_sanitizer::sanitizeTextLine('short text', 250));
+    }
+
+    public function testNullReturnsEmptyString(): void
+    {
+        $this->assertSame('', economic_export_sanitizer::sanitizeTextLine(null));
+    }
+
+    public function testEmptyReturnsEmptyString(): void
+    {
+        $this->assertSame('', economic_export_sanitizer::sanitizeTextLine(''));
+    }
+
+    public function testWhitespaceOnlyReturnsEmptyString(): void
+    {
+        $this->assertSame('', economic_export_sanitizer::sanitizeTextLine("   \t\n  "));
+    }
+
+    public function testWhitespaceOnlyWithSlashesReturnsEmptyString(): void
+    {
+        // After all transformations, "///" becomes "---"
+        // After trim of whitespace-only, "   /   " becomes "" (since / is replaced but space was there)
+        // Actually let's see: "   /   " -> " " stays; "   -   " -> "-"; then trim -> "-"
+        // So it doesn't become empty in this case. Let me re-test:
+        $result = economic_export_sanitizer::sanitizeTextLine('   /   ');
+        $this->assertSame('-', $result);
+    }
+
+    public function testHandlesMultibyteChars(): void
+    {
+        $this->assertSame('æøå', economic_export_sanitizer::sanitizeTextLine('æøå'));
+        $this->assertSame('中文', economic_export_sanitizer::sanitizeTextLine('中文'));
+        $this->assertSame('🚗 car', economic_export_sanitizer::sanitizeTextLine('🚗 car'));
+    }
+
+    public function testTruncationRespectsMultibyteBoundaries(): void
+    {
+        $text = str_repeat('æ', 300);
+        $result = economic_export_sanitizer::sanitizeTextLine($text, 10);
+        $this->assertSame(10, mb_strlen($result));
+        $this->assertStringEndsWith('...', $result);
+    }
+
+    public function testHtmlTagsAreNotStripped(): void
+    {
+        // We don't strip HTML — that's a different concern (XSS). We just sanitize for e-conomic.
+        // The "/" in </b> gets replaced with "-" (per the rules).
+        $this->assertSame('<b>notags<-b>', economic_export_sanitizer::sanitizeTextLine('<b>notags</b>'));
+    }
+
+    public function testSlashesInTheMiddleOfValueAreReplaced(): void
+    {
+        $this->assertSame('foo-bar-baz', economic_export_sanitizer::sanitizeTextLine('foo/bar/baz'));
+    }
+
+    public function testMultipleProblemCharsCombined(): void
+    {
+        $input = "AB/\nC\t\rD\x00E ";
+        $result = economic_export_sanitizer::sanitizeTextLine($input);
+        // After: strip control -> "AB/\nC\tDE ", tab->space -> "AB/\nC DE ",
+        // newline->space -> "AB/ C DE ", slash->dash -> "AB- C DE ",
+        // collapse spaces -> "AB- C DE ", trim -> "AB- C DE"
+        $this->assertSame('AB- C DE', $result);
+    }
+
+    public function testIntegerIsConvertedToString(): void
+    {
+        $this->assertSame('42', economic_export_sanitizer::sanitizeTextLine(42));
+    }
+
+    public function testFloatIsConvertedToString(): void
+    {
+        $this->assertSame('3.14', economic_export_sanitizer::sanitizeTextLine(3.14));
+    }
+
+    // ========================================================================
+    // sanitizeProductNumber
+    // ========================================================================
+
+    public function testProductNumberRemovesPathSeparators(): void
+    {
+        $this->assertSame('ABCDEF', economic_export_sanitizer::sanitizeProductNumber('ABC/DEF'));
+        $this->assertSame('ABCDEF', economic_export_sanitizer::sanitizeProductNumber('ABC\\DEF'));
+    }
+
+    public function testProductNumberRemovesForbiddenChars(): void
+    {
+        $input = "PROD:01?*<>|\"";
+        $result = economic_export_sanitizer::sanitizeProductNumber($input);
+        $this->assertSame('PROD01', $result);
+    }
+
+    public function testProductNumberTruncatesAt50Chars(): void
+    {
+        $text = str_repeat('a', 100);
+        $result = economic_export_sanitizer::sanitizeProductNumber($text);
+        $this->assertSame(50, mb_strlen($result));
+    }
+
+    public function testProductNumberTrimsWhitespace(): void
+    {
+        $this->assertSame('PROD01', economic_export_sanitizer::sanitizeProductNumber('  PROD01  '));
+    }
+
+    public function testProductNumberStripsControlChars(): void
+    {
+        $this->assertSame('PROD01', economic_export_sanitizer::sanitizeProductNumber("PROD\x0001"));
+    }
+
+    public function testProductNumberNullReturnsEmpty(): void
+    {
+        $this->assertSame('', economic_export_sanitizer::sanitizeProductNumber(null));
+    }
+
+    public function testProductNumberAllForbiddenReturnsEmpty(): void
+    {
+        $this->assertSame('', economic_export_sanitizer::sanitizeProductNumber('///\\\\::'));
+    }
+
+    public function testProductNumberKeepsDotsAndDashes(): void
+    {
+        $this->assertSame('PROD-01.0', economic_export_sanitizer::sanitizeProductNumber('PROD-01.0'));
+    }
+
+    // ========================================================================
+    // sanitizeProductDescription
+    // ========================================================================
+
+    public function testProductDescriptionTruncatesAt500(): void
+    {
+        $text = str_repeat('a', 1000);
+        $result = economic_export_sanitizer::sanitizeProductDescription($text);
+        $this->assertSame(500, mb_strlen($result));
+    }
+
+    public function testProductDescriptionReplacesSlashes(): void
+    {
+        $this->assertSame('foo-bar-baz', economic_export_sanitizer::sanitizeProductDescription('foo/bar/baz'));
+    }
+
+    // ========================================================================
+    // sanitizeForEconApi
+    // ========================================================================
+
+    public function testSanitizeForEconApiIsAliasForTextLine(): void
+    {
+        $this->assertSame(
+            economic_export_sanitizer::sanitizeTextLine('foo/bar'),
+            economic_export_sanitizer::sanitizeForEconApi('foo/bar')
+        );
+    }
+}