{"id":8493,"date":"2026-02-19T14:00:12","date_gmt":"2026-02-19T12:00:12","guid":{"rendered":"https:\/\/support.simplbooks.fi\/fi\/kayttoohjeet\/why-cant-i-add-a-product-to-a-sales-invoice\/"},"modified":"2026-02-19T14:00:12","modified_gmt":"2026-02-19T12:00:12","slug":"why-cant-i-add-a-product-to-a-sales-invoice","status":"publish","type":"ht_kb","link":"https:\/\/support.simplbooks.fi\/fi\/en\/kayttoohjeet\/why-cant-i-add-a-product-to-a-sales-invoice\/","title":{"rendered":"Why Can&#8217;t I Add a Product to a Sales Invoice?"},"content":{"rendered":"\n<p><strong>This guide explains why a product cannot be added to a sales invoice and how to resolve the situation.<\/strong><\/p>\n\n\n\n<div class=\"su-note\"  style=\"border-color:#c0d6c5;border-radius:8px;-moz-border-radius:8px;-webkit-border-radius:8px;\"><div class=\"su-note-inner su-u-clearfix su-u-trim\" style=\"background-color:#DAF0DF;border-color:#ffffff;color:#333333;border-radius:8px;-moz-border-radius:8px;-webkit-border-radius:8px;\"> SimplBooks has two different product types: <strong>inventory products and service products.<\/strong> <\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>An inventory product<\/strong> can only be added to a sales invoice if it is in stock. If the inventory balance is zero, the product cannot be added to the invoice. <\/li>\n\n\n\n<li><strong>Service products<\/strong>, on the other hand, can be added to sales invoices without any stock balance. <\/div><\/div><\/li>\n<\/ul>\n\n\n\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<div class=\"su-note\"  style=\"border-color:#c0d6c5;border-radius:8px;-moz-border-radius:8px;-webkit-border-radius:8px;\"><div class=\"su-note-inner su-u-clearfix su-u-trim\" style=\"background-color:#DAF0DF;border-color:#ffffff;color:#333333;border-radius:8px;-moz-border-radius:8px;-webkit-border-radius:8px;\">\ud83d\udce2 <strong>Note!<\/strong> Using inventory tracking adds complexity to your bookkeeping, and we recommend using it only when it adds value to your business. <\/div><\/div>\n\n\n\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\" \/>\n\n\n\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<div class=\"su-spoiler su-spoiler-style-modern su-spoiler-icon-chevron su-spoiler-closed\" data-scroll-offset=\"0\" data-anchor-in-url=\"no\"><div class=\"su-spoiler-title\" tabindex=\"0\" role=\"button\"><span class=\"su-spoiler-icon\"><\/span>What is an inventory product?<\/div><div class=\"su-spoiler-content su-u-clearfix su-u-trim\"><br>Inventory products are linked to stock and appear in the balance sheet under the inventory account. When you add an inventory product to a sales invoice, the system checks whether the product is in stock. If the inventory balance is zero, the product cannot be added to the invoice.<\/p>\n\n\n\n<p>You can add items to inventory either via a <a href=\"https:\/\/support.simplbooks.fi\/fi\/kayttoohjeet\/uuden-ostolaskun-tekeminen\/\" target=\"_blank\" rel=\"noreferrer noopener\">purchase invoice<\/a> or by <a href=\"https:\/\/support.simplbooks.fi\/fi\/kayttoohjeet\/alkuvaraston-lisaaminen\/\" target=\"_blank\" rel=\"noreferrer noopener\">adding opening inventory<\/a>. <\/p>\n\n\n\n<p>You can read about adding a new product to inventory in <a href=\"https:\/\/support.simplbooks.fi\/fi\/kayttoohjeet\/myytavan-tuotteen-lisaaminen\/\" target=\"_blank\" rel=\"noreferrer noopener\">this guide<\/a> (step 2).<\/p>\n\n\n\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<div class=\"su-note\"  style=\"border-color:#c0d6c5;border-radius:8px;-moz-border-radius:8px;-webkit-border-radius:8px;\"><div class=\"su-note-inner su-u-clearfix su-u-trim\" style=\"background-color:#DAF0DF;border-color:#ffffff;color:#333333;border-radius:8px;-moz-border-radius:8px;-webkit-border-radius:8px;\"> \ud83d\udce2 <strong>Note!<\/strong> When purchasing goods into inventory and selling goods from inventory, <strong>the purchase invoice date must be earlier than the sales invoice date.<\/strong><\/p>\n\n\n\n<p>An exception applies when negative inventory balances have been allowed in the warehouse settings. You can check this at <strong>Settings<\/strong> &gt; <strong>Environment Settings<\/strong> &gt; <strong>Warehouse Settings<\/strong> &gt; <strong>Inventory quantity can be negative<\/strong>.  <\/div><\/div>\n\n\n\n<\/div><\/div>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\" \/>\n\n\n\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<div class=\"su-spoiler su-spoiler-style-modern su-spoiler-icon-chevron su-spoiler-closed\" data-scroll-offset=\"0\" data-anchor-in-url=\"no\"><div class=\"su-spoiler-title\" tabindex=\"0\" role=\"button\"><span class=\"su-spoiler-icon\"><\/span>What is a service product?<\/div><div class=\"su-spoiler-content su-u-clearfix su-u-trim\"><br>Service products are not linked to inventory and can be added to sales invoices freely. If you sell services and add products to the system, always add them as service products.<\/p>\n\n\n\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<div class=\"su-note\"  style=\"border-color:#c0d6c5;border-radius:8px;-moz-border-radius:8px;-webkit-border-radius:8px;\"><div class=\"su-note-inner su-u-clearfix su-u-trim\" style=\"background-color:#DAF0DF;border-color:#ffffff;color:#333333;border-radius:8px;-moz-border-radius:8px;-webkit-border-radius:8px;\">\ud83d\udca1 <strong>Tip<\/strong>: If you do not want to use inventory tracking, you can also add physical products as service products. <\/div><\/div>\n\n\n\n<\/div><\/div>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\" \/>\n\n\n\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<div class=\"su-spoiler su-spoiler-style-modern su-spoiler-icon-chevron su-spoiler-closed\" data-scroll-offset=\"0\" data-anchor-in-url=\"no\"><div class=\"su-spoiler-title\" tabindex=\"0\" role=\"button\"><span class=\"su-spoiler-icon\"><\/span>Can I change a product that has already been added?<\/div><div class=\"su-spoiler-content su-u-clearfix su-u-trim\"><br>If you no longer want to use inventory tracking for an already-added product, you can edit it to become a non-inventory product at <strong>Inventory<\/strong> &gt; <strong>Products<\/strong>. <\/p>\n\n\n\n<p>Open the product by clicking on it.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><a href=\"https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/1-25.png\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"361\" src=\"https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/1-25-1024x361.png\" alt=\"\" class=\"wp-image-8001\" srcset=\"https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/1-25-1024x361.png 1024w, https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/1-25-300x106.png 300w, https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/1-25-768x270.png 768w, https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/1-25-50x18.png 50w, https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/1-25-1536x541.png 1536w, https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/1-25-920x324.png 920w, https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/1-25-600x211.png 600w, https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/1-25-320x113.png 320w, https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/1-25.png 1582w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/a><\/figure>\n\n\n\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<p>Select &#8220;<strong>Edit product<\/strong>&#8221; on the right side.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><a href=\"https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/2-24.png\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"300\" src=\"https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/2-24-1024x300.png\" alt=\"\" class=\"wp-image-8003\" srcset=\"https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/2-24-1024x300.png 1024w, https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/2-24-300x88.png 300w, https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/2-24-768x225.png 768w, https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/2-24-50x15.png 50w, https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/2-24-1536x450.png 1536w, https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/2-24-920x269.png 920w, https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/2-24-600x176.png 600w, https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/2-24-320x94.png 320w, https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/2-24.png 1584w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/a><\/figure>\n\n\n\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<p>Change the product from an inventory product to a service product and save.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><a href=\"https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/3-19.png\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"470\" src=\"https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/3-19-1024x470.png\" alt=\"\" class=\"wp-image-8005\" srcset=\"https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/3-19-1024x470.png 1024w, https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/3-19-300x138.png 300w, https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/3-19-768x353.png 768w, https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/3-19-50x23.png 50w, https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/3-19-1536x705.png 1536w, https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/3-19-920x423.png 920w, https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/3-19-600x276.png 600w, https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/3-19-320x147.png 320w, https:\/\/support.simplbooks.fi\/fi\/wp-content\/uploads\/2024\/03\/3-19.png 1596w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/a><\/figure>\n\n\n\n<\/div><\/div>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\" \/>\n\n\n\n<div style=\"height:35px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<div class=\"su-box su-box-style-default\" id=\"\" style=\"border-color:#a7bdac;border-radius:8px\"><div class=\"su-box-title\" style=\"background-color:#DAF0DF;color:#333333;border-top-left-radius:6px;border-top-right-radius:6px\">Other related guides:<\/div><div class=\"su-box-content su-u-clearfix su-u-trim\" style=\"border-bottom-left-radius:6px;border-bottom-right-radius:6px\">\n\n\n\n<div class=\"su-list\" style=\"margin-left:0px\">\n\n\n\n<ul class=\"wp-block-list\">\n<li><i class=\"sui sui-book\" style=\"color:#333\"><\/i> <a href=\"http:\/\/support.simplbooks.fi\/fi\/kayttoohjeet\/myytavan-tuotteen-lisaaminen\/\" target=\"_blank\" rel=\"noreferrer noopener\">Adding a product for sale<\/a><\/li>\n\n\n\n<li><i class=\"sui sui-book\" style=\"color:#333\"><\/i> <a href=\"http:\/\/support.simplbooks.fi\/fi\/kayttoohjeet\/alkuvaraston-lisaaminen\/\" target=\"_blank\" rel=\"noreferrer noopener\">Adding opening inventory<\/a><\/li>\n\n\n\n<li><i class=\"sui sui-book\" style=\"color:#333\"><\/i> <a href=\"http:\/\/support.simplbooks.fi\/fi\/kayttoohjeet\/tuotteiden-siirtaminen-varastosta-toiseen\/\" target=\"_blank\" rel=\"noreferrer noopener\">Transferring products between warehouses<\/a><\/li>\n\n\n\n<li><i class=\"sui sui-book\" style=\"color:#333\"><\/i> <a href=\"http:\/\/support.simplbooks.fi\/fi\/kayttoohjeet\/tuotteiden-vahentaminen-varastosta\/\" target=\"_blank\" rel=\"noreferrer noopener\">Reducing products from inventory<\/a><\/li>\n<\/ul>\n\n\n\n<\/div><\/div><\/div>\n\n\n\n<div style=\"height:40px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n","protected":false},"author":0,"comment_status":"open","ping_status":"closed","template":"","format":"standard","meta":{"footnotes":""},"ht_kb_category":[115],"ht_kb_tag":[],"class_list":["post-8493","ht_kb","type-ht_kb","status-publish","format-standard","hentry","ht_kb_category-sales"],"_links":{"self":[{"href":"https:\/\/support.simplbooks.fi\/fi\/en\/wp-json\/wp\/v2\/ht_kb\/8493","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/support.simplbooks.fi\/fi\/en\/wp-json\/wp\/v2\/ht_kb"}],"about":[{"href":"https:\/\/support.simplbooks.fi\/fi\/en\/wp-json\/wp\/v2\/types\/ht_kb"}],"replies":[{"embeddable":true,"href":"https:\/\/support.simplbooks.fi\/fi\/en\/wp-json\/wp\/v2\/comments?post=8493"}],"version-history":[{"count":0,"href":"https:\/\/support.simplbooks.fi\/fi\/en\/wp-json\/wp\/v2\/ht_kb\/8493\/revisions"}],"wp:attachment":[{"href":"https:\/\/support.simplbooks.fi\/fi\/en\/wp-json\/wp\/v2\/media?parent=8493"}],"wp:term":[{"taxonomy":"ht_kb_category","embeddable":true,"href":"https:\/\/support.simplbooks.fi\/fi\/en\/wp-json\/wp\/v2\/ht_kb_category?post=8493"},{"taxonomy":"ht_kb_tag","embeddable":true,"href":"https:\/\/support.simplbooks.fi\/fi\/en\/wp-json\/wp\/v2\/ht_kb_tag?post=8493"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}