How to file the SA100 Self-Assessment Return

What is form SA100?

The SA100 return, more commonly known as the Self-Assessment Tax Return, is a tax return for individuals to complete in order to determine how much income tax they need to pay. This is typically used by individuals who are self-employed (such as sole traders), or employees who are not paid through PAYE (Pay As You Earn).

The PAYE scheme is a common scheme that most employers use, as it means that the tax that is due is already deducted from your salary each month, rather than having to pay it all together at the end of the year. For example, if you are a sole trader, the only employee of your business, the director of an LLP or earning untaxed commission or tips, and you pay yourself a salary or are responsible for paying your own tax, then you will need to complete the self assessment for tax at the end of every year.

For directors of limited companies or partnerships, read our article  Do I Need to File a Self-Assessment Return as a Company Director? for more information.

Filing the SA100 form

HMRC require the SA100 return to be submitted online rather than on paper, but If you are unable to submit digitally, then you will need to request that HMRC send a paper copy of the return to your address, as you cannot print your own copy of the form, as they need to know you are submitting by post. Find out more about ordering forms from HMRC.

When are the returns due?

There are deadlines for notifying HMRC that you need to complete a tax return, and for submitting the completed SA100 form either by post or online. The table below outlines the deadlines based on the tax year which starts on April 5th for the current tax year.

Basic Deadlines*:

*This is based on if you are submitting a return for the tax year that ran from 6th April 2023 to 5th April 2024 (so the Financial Year 23/24).

If the tax return or tax is not submitted/paid by the due date, then you may be subject to receive a late filing penalty. You can find out more about HMRC's self-assessment deadlines here.

Using our Self Assessment software

Easy Digital Filing allows you to file the SA100 return online on the platform. Simply log on/ or register an account, and add the SA100 return filing to get started!

Step 1:   Add the template to your account

You can find this template by clicking on the blue 'Add Filing' button near the top-right hand side of the screen. A template menu will appear - select 'Individual' from the 'Show Me:' drop-down options near the top right-hand side of the box. From there, you can select the 'Self Assessment: Personal Tax Return (SA100)' template and add it to your account.

Step 2:   Complete the 'Return Details' page

The first step is to complete the 'Return Details' page, which contains basic information, such as your name, date of birth, UTR number, and more.

Step 3:   Complete the 'Tax Calculation' page

Similar to the CT600 return templates, there is a tax calculation page on the SA100 return. This is the main page where you will enter any basic income, then, if you have other income, such as income from employment or income from a partnership, you can click on the calculator icon next to the headings and they will take you to those pages.

You can also find the other pages by heading to the 'Additional Sections' tab and switching the relevant boxes to 'Yes'.

Step 3:   Additional Sections

If you require any of the additional sections or pages, you can find these within the 'Additional Sections' tab. Within the main form, you can add the 'Other Income', 'Relief and Allowances', 'Payments and Repayments', or 'Supporting Documents' sections as well.

Furthermore, we also offer two of the additional forms, which are the SA102 (which is for income from employment), or the SA104S (which is for income from partnerships).

Simply switch any of the boxes to 'Yes' and a new tab will be created on the left-hand side of the template, where you can then go to the relevant page.

Step 4:   Complete the 'Declaration' page

The next step is to complete the 'Declaration' page. In this page, you just need to enter some more basic information about the return, such as who is signing it, or whether it is an amended return, etc.

Step 5:   Submit!

Once you are happy with the filing and are ready to submit, you can set the filing as 'Ready to File' by clicking on the green button near the bottom of the filing. Then, once back on the 'Filings View' screen, you can click on the credit card icon under the 'Submit/Result' column to go to the correct package.

The SA100 return costs £20 + VAT to submit through our software - you can also find this package under the 'Purchase Services' tab in your account and selecting the package called 'SA100 Personal Tax Digital Filing Return'.

Once the package has been purchased, the credits are automatically assigned to your filings, so that you can submit them whenever you're ready. To submit, simply click on the flashing 'play' button under the Submit/Result column next to your filing (it will be where the credit card icon was before).

This will then open a pop-up box confirming the details within the return, before clicking on 'Submit Filing' to HMRC'. Once submitted, the filing is processed and is either accepted or rejected by HMRC. In both instances, a box will appear either confirming that the filing has been accepted or explaining the reason for the rejection. The symbol under the 'Submit/Result' column will update accordingly.

SA100 notes to remember:

While completing your filings, it is important to keep track of the filing deadlines so that you can avoid late filing penalties. When filing through our software, the return needs to be submitted by 31st January the year after the end of the Financial Year. However, if you are choosing to submit your return by paper instead, the due date is the 31st October of the same year that the Financial Year ended.

Following the steps listed above, you should now be able to successfully submit your self-assessment tax return to HMRC through our software! If you do not already have an account with us, you can create one for free at Easy Digital Filing to get started.