{"id":562,"date":"2019-06-26T16:49:32","date_gmt":"2019-06-26T15:49:32","guid":{"rendered":"https:\/\/taxfix.com\/en-uk\/?p=562"},"modified":"2025-04-07T15:39:40","modified_gmt":"2025-04-07T14:39:40","slug":"what-is-the-sa103-form","status":"publish","type":"post","link":"https:\/\/taxfix.com\/en-uk\/self-assessment-basics\/what-is-the-sa103-form\/","title":{"rendered":"How to complete the SA103 self-employment tax return form"},"content":{"rendered":"\n<p>The <a href=\"\/en-uk\/glossary\/sa103\/\">SA103 form<\/a> is the document you need to complete so you can&nbsp;<a href=\"\/en-uk\/self-employed-taxes\/\">pay tax on income from self-employment<\/a>.<\/p>\n\n\n\n<p>There are two kinds of SA103:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The short version, called <strong>SA103S<\/strong>, which can be used by most self-employed people<\/li>\n\n\n\n<li>The &#8220;full version&#8221;, called <strong>SA103F<\/strong>, which is used by sole traders with more complex situations (they earn over the VAT limit, are a practising barrister, <a href=\"\/en-uk\/self-employed-cash-basis-traditional-accounting\/\">use traditional accounting instead of the usual cash basis<\/a>, etc.)<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">How do I know if I&#8217;m self-employed (sole trader)?<\/h2>\n\n\n\n<p>It&#8217;s not always as easy as it sounds. Self-employed is a broad term, often referring both to limited companies and sole traders. Here&#8217;s how to work out whether or not you&#8217;re a sole trader.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Are you working with a full-time employment contract? Then you&#8217;re not a sole trader<\/li>\n\n\n\n<li>Are you using a limited company to do business? Then you&#8217;re an employee of your own company (or an umbrella company), but not a sole trader<\/li>\n<\/ul>\n\n\n\n<p>Also, in case you&#8217;re wondering, the term <strong>&#8220;sole trader&#8221; is often used interchangeably with the term &#8220;self-employed&#8221;<\/strong>.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">How do I fill it in?<\/h2>\n\n\n\n<p>You can get the &#8220;shorter&#8221; SA103S form from\u00a0<a href=\"https:\/\/www.gov.uk\/government\/publications\/self-assessment-self-employment-short-sa103s\">this HMRC page<\/a>.<\/p>\n\n\n\n<p>If you file a Self Assessment tax return every year, then HMRC might also send it to you.<\/p>\n\n\n\n<p>In any case,\u00a0<strong>make sure you first read the \u201cSelf-employment (notes)\u201d pdf<\/strong>\u00a0for that tax year \u2013 it\u2019s on the same HMRC page.It explains what each line item on the form means, and how to fill it.<\/p>\n\n\n\n<p>If you want the full version, <a href=\"https:\/\/www.gov.uk\/government\/publications\/self-assessment-self-employment-full-sa103f\">download the SA103F form here<\/a> instead.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">How do I submit it?<\/h2>\n\n\n\n<p>You need to send it together with your&nbsp;<a href=\"https:\/\/taxfix.com\/en-uk\/what-is-the-sa100-form\/\">SA100 form<\/a> (the main tax return form)&nbsp;\u2013 you can\u2019t file the SA103 by itself.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Can I send it to HMRC online?<\/h2>\n\n\n\n<p>No, you need to send it by post.<\/p>\n\n\n\n<p>The good news is that you can choose to do your entire Self Assessment online. Plus you can get another 3 months to do it since the deadline for sending the paper form is October 31st, but <a href=\"https:\/\/taxfix.com\/en-uk\/uk-tax-year-dates-and-filing-deadlines\/\">for online tax returns is 3 months later<\/a>&nbsp;(end of January).<\/p>\n\n\n<\/div> <!-- .c-body -->\n\n<div class=\"b-highlight-mini m-neutral m-align-left\">\n    <div class=\"b-block-body\">\n        <p><span style=\"font-weight: 400;\">Key dates in the current <\/span><b>2025\/26 tax year \ud83d\udc47<\/b><\/p>\n<table>\n<tbody>\n<tr>\n<td><b>Deadline<\/b><\/td>\n<td><b>Date<\/b><\/td>\n<td><b>Year<\/b><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400;\">Tax year starts<\/span><\/td>\n<td><span style=\"font-weight: 400;\">6th April<\/span><\/td>\n<td><span style=\"font-weight: 400;\">2025<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400;\">Tax year ends<\/span><\/td>\n<td><span style=\"font-weight: 400;\">5th April<\/span><\/td>\n<td><span style=\"font-weight: 400;\">2026<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400;\">Register for self assessment<\/span><\/td>\n<td><span style=\"font-weight: 400;\">5th October<\/span><\/td>\n<td><span style=\"font-weight: 400;\">2026<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400;\">Pay tax bill by PAYE salary<\/span><\/td>\n<td><span style=\"font-weight: 400;\">30th December<\/span><\/td>\n<td><span style=\"font-weight: 400;\">2026<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400;\">Self assessment deadline<\/span><\/td>\n<td><span style=\"font-weight: 400;\">31st January<\/span><\/td>\n<td><span style=\"font-weight: 400;\">2027<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\n    <\/div>\n<\/div> <!-- .b-highlight-mini -->\n\n<div class=\"c-body\">\n\n\n\n\n\n<p>At Taxfix&nbsp;<a href=\"https:\/\/taxfix.com\/en-uk\/\">we can file your tax return online for you<\/a>&nbsp;instead \u2013 and for a flat fee, regardless of how many sources of income you have.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>The SA103 form is the document you need to complete so you can&nbsp;pay tax on income from self-employment. There are two kinds of SA103: How do I know if I&#8217;m self-employed (sole trader)? It&#8217;s not always as easy as it sounds. Self-employed is a broad term, often referring both to limited companies and sole traders. [&hellip;]<\/p>\n","protected":false},"author":9,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[437,435],"tags":[102,411,415],"class_list":["post-562","post","type-post","status-publish","format-standard","hentry","category-documents-and-forms","category-self-assessment-basics","tag-hmrc","tag-self-employed","tag-tax-return-basics"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v25.8 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>How to complete the SA103 self-employment tax return form &#8211; Taxfix<\/title>\n<meta name=\"description\" content=\"Between the SA103S and SA103F, self-employment taxes can be confusing. 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For a quick breakdown of what form you need to submit, read here!\" \/>\n<meta property=\"og:url\" content=\"https:\/\/taxfix.com\/en-uk\/self-assessment-basics\/what-is-the-sa103-form\/\" \/>\n<meta property=\"og:site_name\" content=\"Taxfix\" \/>\n<meta property=\"article:publisher\" content=\"https:\/\/www.facebook.com\/taxfix_uk\" \/>\n<meta property=\"article:published_time\" content=\"2019-06-26T15:49:32+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2025-04-07T14:39:40+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/taxfix.com\/en-uk\/wp-content\/uploads\/eyJhc3NldF9pZCI6NTY3OH0_taxfix-gmbh_UwIjumOzeyPqNyDgJ1bVY_OROVADgg2mBtzSX1XQ7A0.jpg\" \/>\n\t<meta property=\"og:image:width\" content=\"1200\" \/>\n\t<meta property=\"og:image:height\" content=\"628\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/jpeg\" \/>\n<meta name=\"author\" content=\"Gemma Doswell\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:creator\" content=\"@Taxfix\" \/>\n<meta name=\"twitter:site\" content=\"@Taxfix\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\/\/taxfix.com\/en-uk\/self-assessment-basics\/what-is-the-sa103-form\/\",\"url\":\"https:\/\/taxfix.com\/en-uk\/self-assessment-basics\/what-is-the-sa103-form\/\",\"name\":\"How to complete the SA103 self-employment tax return form &#8211; Taxfix\",\"isPartOf\":{\"@id\":\"https:\/\/taxfix.com\/en-uk\/#website\"},\"datePublished\":\"2019-06-26T15:49:32+00:00\",\"dateModified\":\"2025-04-07T14:39:40+00:00\",\"author\":{\"@id\":\"https:\/\/taxfix.com\/en-uk\/#\/schema\/person\/008d0d859b00d5809e35d143dff5dd4a\"},\"description\":\"Between the SA103S and SA103F, self-employment taxes can be confusing. 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