{"id":97,"date":"2023-10-23T11:36:51","date_gmt":"2023-10-23T10:36:51","guid":{"rendered":"https:\/\/taxfix.com\/en-uk\/?p=97"},"modified":"2025-10-06T15:50:07","modified_gmt":"2025-10-06T14:50:07","slug":"common-self-assessment-mistakes","status":"publish","type":"post","link":"https:\/\/taxfix.com\/en-uk\/self-assessment-basics\/common-self-assessment-mistakes\/","title":{"rendered":"The most common Self Assessment mistakes"},"content":{"rendered":"\n<p>You can make filing your taxes much easier by avoiding these common Self Assessment mistakes:<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">1. Forgetting about deadlines<\/h2>\n\n\n\n<p><a href=\"https:\/\/taxfix.com\/en-uk\/how-to-get-utr\">You need a UTR number<\/a>&nbsp;for your Self Assessment.<\/p>\n\n\n\n<p>It takes weeks to get it, so don&#8217;t wait until the last minute.<\/p>\n\n\n\n<p>If you&#8217;re not sure about the deadlines,&nbsp;<a href=\"https:\/\/taxfix.com\/en-uk\/uk-tax-year-dates-and-filing-deadlines\">check our post on the UK tax year dates here<\/a>.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">2. Forgetting about tax reliefs<\/h2>\n\n\n\n<p>There are many ways to reduce your tax bill.<\/p>\n\n\n\n<p>You should:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>keep a list of all the claimable expenses (especially&nbsp;<a href=\"https:\/\/taxfix.com\/en-uk\/self-employed-claimable-expenses\">if you&#8217;re self-employed<\/a>&nbsp;or&nbsp;<a href=\"https:\/\/taxfix.com\/en-uk\/allowable-property-expenses-for-rental-income\">a landlord<\/a>)<\/li>\n\n\n\n<li>make full use of your&nbsp;<a href=\"https:\/\/taxfix.com\/en-uk\/list-of-tax-free-allowances\">tax-free allowances<\/a><\/li>\n\n\n\n<li>declare money you\u2019ve given to charities<\/li>\n\n\n\n<li>claim your private pension contributions.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">3. Forgetting about payments on account<\/h2>\n\n\n\n<p>HMRC may ask you to pay this year&#8217;s bill and also a&nbsp;<strong>&#8220;<a href=\"\/en-uk\/glossary\/payment-on-account\/\">Payment on Account<\/a>.&#8221;<\/strong><\/p>\n\n\n\n<p>Your first January payment could be 50% bigger than you think.<\/p>\n\n\n\n<p>If you&#8217;re&nbsp;self-employed, remember that payments on account are charged at the end of January and the end of July. <\/p>\n\n\n\n<p>Read&nbsp;<a href=\"https:\/\/taxfix.com\/en-uk\/what-is-a-payment-on-account\">our guide to Payments on Account here<\/a>.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">4. Getting your tax code wrong<\/h2>\n\n\n\n<p>If you are under the wrong tax code, you could be paying too much tax.<\/p>\n\n\n\n<p>Check our post on&nbsp;<a href=\"https:\/\/taxfix.com\/en-uk\/what-does-the-tax-code-mean\">what your tax code means and how to find it<\/a>.<\/p>\n\n\n\n<p>If there&#8217;s a mistake,\u00a0call HMRC\u00a0as soon as possible.<\/p>\n\n\n<div data-react=\"tooltip-provider\"><\/div>\n\n    <div class=\"c-block-calculator\">\n\n    <div class=\"c-block-calculator__container\">\n\n\n    <div data-react=\"tax-code-calculator\" data-options='{\n        \"title\": \"Tax code checker\",\n        \"lead\": \"Tell us your tax code and salary and we&#039;ll let you know what it all means.\"\n    }'>\n        <!-- Default calc code -->\n\n        <div class=\"sc-giYgFv fzUHXQ\"><div class=\"sc-ezbkgU bcxCiI\"><div class=\"sc-bYoCmx RakSM\"><div width=\"100%\" aria-expanded=\"false\" class=\"DropdownSelect__Container-sc-1iiysit-0 evEFoA\"><button width=\"100%\" class=\"DropdownSelect__LabelContainer-sc-1iiysit-1 egNJwI\"><span class=\"DropdownSelect__Label-sc-1iiysit-2 loOBxi\">Tax year 2024\/25<\/span> <span class=\"DropdownSelect__Arrow-sc-1iiysit-3 hcHQYJ\">\u25bc<\/span><\/button><\/div><\/div><\/div><div class=\"sc-dPiKHq jvrqXK\"><div class=\"sc-bBHHQT eyRCSV\"><h3 class=\"sc-khQdMy idLFkV\">Your situation<\/h3><img decoding=\"async\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMzQiIGhlaWdodD0iNzYiIHZpZXdCb3g9IjAgMCAzNCA3NiIgZmlsbD0ibm9uZSIgeG1sbnM9Imh0dHA6Ly93d3cudzMub3JnLzIwMDAvc3ZnIj48cGF0aCBkPSJNMzIuMjUgMzQuOTMzNVYxLjg0OTYxSDIwLjE0OTlDMTcuNzQ5OSA5LjA0OTYxIDExLjA1IDEzLjY0OTYgMS43NSAxNC4xNDk2VjI2Ljk0OTZDNy45NSAyNi45NDk2IDEzLjg0OTkgMjUuMDQ5NiAxNy44NDk5IDIxLjg0OTZWMzQuOTMzNU0xNy44NDk5IDU1LjUxODhWNzQuMDQ5NkgzMi4yNVY1OS40OTQ1VjU1LjUxODgiIHN0cm9rZT0iYmxhY2siIHN0cm9rZS13aWR0aD0iMiIgc3Ryb2tlLWxpbmVjYXA9InJvdW5kIiBzdHJva2UtbGluZWpvaW49InJvdW5kIi8+PC9zdmc+\" alt=\"Outlined number one\" class=\"sc-cNKpQo gvneOt\"><img decoding=\"async\" src=\"data:image\/svg+xml;base64,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\" alt=\"Image of an arrow\" class=\"sc-AjmZR ctylzc\"><\/div><div class=\"sc-hUpaWb\"><form><div class=\"sc-kLwgWK gVgARU\"><div class=\"Form__FormRowTitle-sc-32vt5e-2 coHrqe\">Tax code <div class=\"sc-eJwXpk byFCvI\"><span data-hint-default=\"Not sure what your tax code is? Check HMRC online or a recent PAYE coding notice, payslip, P45, P60 or pension advice slip\"><div class=\"sc-nVjpj eKPbQR\">?<\/div><\/span><\/div><\/div><div class=\"Form__FormRowItem-sc-32vt5e-3\"><div class=\"Input__Container-sc-11yg3hb-0 jiJACg\"><input name=\"taxCode\" class=\"Input__InputElement-sc-11yg3hb-1 hA-dEwl\"><\/div><\/div><\/div><div class=\"sc-kLwgWK gVgARU\"><div class=\"Form__FormRowTitle-sc-32vt5e-2 coHrqe\">Annual salary<\/div><div class=\"Form__FormRowItem-sc-32vt5e-3\"><div class=\"Input__Container-sc-11yg3hb-0 jiJACg\"><input type=\"number\" min=\"0\" pattern=\"[0-9]*\" name=\"annualIncome\" class=\"Input__InputElement-sc-11yg3hb-1 gvuJbz\"><div class=\"Input__Suffix-sc-11yg3hb-4 eEnjn\">\u00a3<\/div><\/div><\/div><\/div><button disabled=\"\" type=\"button\" class=\"Button__Container-sc-1yfsg4-0 bsATTQ\"><div class=\"Loadable__Container-sc-113zh66-0 boOZMZ\"><div class=\"Loadable__Overlay-sc-113zh66-1 eNpsGm\"><div class=\"Loadable__SpinnerContainer-sc-113zh66-3 ixfJxf\"><div role=\"progressbar\" aria-busy=\"true\" aria-live=\"polite\" color=\"#003cd7\" class=\"Spinner__Container-sc-1v52frf-0 epXYIp\"><\/div><\/div><\/div><div class=\"Loadable__Content-sc-113zh66-2 dfBZsX\">Calculate<\/div><\/div><\/button><\/form><\/div><\/div><div opacity=\"1\" class=\"sc-jgrIVw gcVyeu\"><div class=\"sc-gSQGeZ mqvVl\"><h3 class=\"sc-iNGGwv dFrXnM\">Results<\/h3><img decoding=\"async\" src=\"data:image\/svg+xml;base64,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\" alt=\"Outlined number two\" class=\"sc-lbhJmS hQoEOj\"><\/div><div class=\"sc-jeqYYF fOQSYu\"><ul class=\"sc-gWXaA-D byUbmH\"><li class=\"sc-cCcYRi TgcgA\"><div class=\"sc-iUKrWq jFZeFw\">PAYE earnings<\/div><div class=\"sc-efQUeY cGxXVa\">\u00a349,000<\/div><\/li><\/ul><\/div><\/div><div class=\"sc-dJjZJu isonvD\"><button class=\"sc-hGPAah fmpGnU\"><img decoding=\"async\" src=\"data:image\/svg+xml;base64,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\" alt=\"Illustration\" class=\"sc-dlVyqM lhOciq\"><div class=\"sc-kfPtPH\"><div class=\"sc-fKVsgm kAXsua\">Calculation details<\/div><div class=\"sc-bBHwJV jdTgMA\"><span>Click here<\/span> to show how we&#8217;ve calculated your taxes<\/div><\/div><\/button><div class=\"sc-iwjezw jVHDsA\"><div class=\"sc-cTApHj\"><div class=\"c-body m-smaller\"><h2>How your tax code is calculated<\/h2><p>There are three main components that determine your tax code:<\/p><ul><li>What you earn<\/li><li>Allowances you&#8217;re claiming<\/li><li>Your tax-free allowances<\/li><\/ul><\/div><\/div><\/div><\/div><\/div>\n\n        <!-- END Default calc code -->\n    <\/div>\n\n\n    <\/div> <!-- .c-container -->\n<\/div> <!-- .c-block-calculator -->\n\n\n\n\n\n<h2 class=\"wp-block-heading\">5. Forgetting to declare salary and benefits from PAYE jobs<\/h2>\n\n\n\n<p><a href=\"\/en-uk\/what-is-paye\/\">If you have a full-time job besides being self-employed<\/a>, you need to let HMRC know so you don&#8217;t pay extra tax.<\/p>\n\n\n\n<p>Ask your employer for a&nbsp;<a href=\"https:\/\/taxfix.com\/en-uk\/what-is-p60-form\">P60<\/a>&nbsp;and <a href=\"\/en-uk\/glossary\/p11d\/\">P11D<\/a>: this will show you how much you earned and how much tax was paid.<\/p>\n\n\n\n<p>You need to record this on the Employment pages of your tax return.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>You can make filing your taxes much easier by avoiding these common Self Assessment mistakes: 1. Forgetting about deadlines You need a UTR number&nbsp;for your Self Assessment. It takes weeks to get it, so don&#8217;t wait until the last minute. If you&#8217;re not sure about the deadlines,&nbsp;check our post on the UK tax year dates [&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":[439,435],"tags":[102,411,29],"class_list":["post-97","post","type-post","status-publish","format-standard","hentry","category-registration-and-filing-your-tax-return","category-self-assessment-basics","tag-hmrc","tag-self-employed","tag-taxscouts"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v25.8 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>The most common Self Assessment mistakes &#8211; Taxfix<\/title>\n<meta name=\"description\" content=\"Doing your taxes is hard - but you can make it easier by avoiding these common self assessment mistakes. You&#039;ll also avoid hefty penalties. 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