As a firm of accountants and advisors, some of the most common questions we hear from new clients are:
If you're asking yourself these questions then you're not alone.
It's common to many business owners, freelancers, and individuals.
The honest answer is that not everyone does but if you should and you then don't, that will cause you financial headache's and problems.
That's why we've produced this blog post, so that you don't have to rely on guesswork and can instead reference this tax return checklist to provide you with a clear indicator as to what you need to do.
A Self Assessment Tax Return is what you use to tell HM Revenue & Customs (HMRC) about any of your income that hasn't already been taxed automatically. In simple terms this means if HMRC doesn't already know about your income through Pay As You Earn (PAYE) then you'll usually need to report it yourself.
Examples of this can include:
If you tick any of the below boxes, then there's a strong chance that you'll need to complete a Self Assessment Tax Return.
a) You're self employed (even part-time)
If you earn more than £1,000 from self-employment, you'll usually need to file a tax return.
This is particularly relevant to:
The above applies even if it's not your main source of income.
b) You're a company director
If you run a limited company, you'll often need to complete a tax return and this is the case especially if you're taking:
c) You have untaxed income
This is a scenario that often catches people out. It's important you understand and remember this, if HMRC haven't already taxed your income, then it's your responsibility to declare it!
Examples of that income can include:
If tax hasn't been deducted then the onus is on you to report it.
d) You've sold assets
If you've sold assets and made a gain then you'll need to report this for Capital Gains Tax. A gain refers to the profit made when you sell, gift, or exchange an asset for more than you paid for it. The increase in value is taxed. Assets can include:
e) HMRC requests one
If you receive a notification from HMRC to complete a return then you must do it. It has to happen even if you don't think you owe anything.
You may not need to file if:
Just be warned, mistakes can easily happen based on assumption that you're covered, when actually you're not!
As mentioned earlier, most personal tax issues don't come from people deliberately ignoring matters. They come from people assuming, and not fully comprehending tax legislation in relation to their personal finances:
'I didn't realise this applied to me'.
Examples of this can include:
So, if this sounds familiar then review this post, consult a tax professional if you're not sure, but above all else, don't just assume you don't need to file a tax return.
Unfortunately many people don't consider this until it's too late. If you fail to complete a tax return when required then:
Furthermore HMRC increasingly has access to more data than people may care to realise. Don't therefore rely on hoping you won't be picked up would be our advice.
Can I just ignore this?
In short, no.
If you're likely to need to be filing then ignoring it can lead to:
If you need to complete a tax return then you usually have to register by 5 October following the end of the tax year in which you made your income.
Don't leave it too late, this delays the whole process and can leave you at risk of penalties.
If you're still unsure if you need to fill in a tax return then consider if the following apply to you:
Here's the thing, by the time you get to January:
You may have ticked one of the bullet points from above. So, now you know a tax return may be needed, but you aren't totally sure as to why. It's sensible to pause and ask this question, better to double check than get things wrong.
That's why we recommend a quick conversation with us which can:
If you think, or you've confirmed, that you need to file a tax return, the next step is to understand:
Here is a link to the tax return page and aide memoire we supply to our clients shortly after the beginning of the new tax year. Whilst considerable, it's an indicative but not exhaustive list of the kinds of items relevant to this process.
So remember, you'll likely need to register and complete a tax return if you:
If none of the above is applicable, you may not need to apply but it's most likely worth checking in with us to make sure.
The content of this post was created on 11/05/2026.
Please be aware that information provided by this blog is subject to regular legal and regulatory change. We recommend that you do not take any information held within our website or guides (eBooks) as a definitive guide to the law on the relevant matter being discussed. We suggest your course of action should be to seek legal or professional advice where necessary rather than relying on the content supplied by the author(s) of this blog.