Self Assessment Explained: A Complete Guide

  •  By
  •  Lee Mannion

Yep, the countdown is on for the 31st, the dreaded Self Assessment tax return. Tax can be complicated, and well, boring but we’re here to help you get ahead of the deadline with our top tips.

What is a Self Assessment?

If you receive income that isn’t taxed at the source, then you’ll need to complete a Self Assessment. For example, if you’re a sole trader, in a business partnership or a company director you’ll need to file one.

Self Assessment is just how HMRC works out how much Income Tax and National Insurance you need to pay on what you’ve earned that year. When you’re employed, Income Tax is deducted automatically from your wage, but this doesn’t happen for self-employed people or for other types of income like pensions, investments and dividends.

How much income tax will I pay?

You’ll have to pay Income Tax on earnings that are over the personal allowance on your income (£12,500) but it depends on how much you’ve earned within the year. Below is a table that shows the % of your earnings you’ll have to pay Income tax on:

A table showing income tax bands and tax rates

There are National Insurance contributions too… This is calculated by HMRC after you’ve submitted your Self Assessment, they’ll say exactly how much you owe for National Insurance and Income Tax.

What do I need in order to complete the Self Assessment?

If this is your first Self Assessment, you would have already registered with HMRC by the 5th of October to tell them that you need to submit a Self Assessment tax return. HMRC would have sent you your Unique Taxpayer Reference (UTR) number in the post, which you’ll need for the return.

You’ll also need to bring a few documents about the income and costs of your company throughout the last year. This includes:

  • Details on your untaxed income (this includes dividends, partnership income, interest from savings or investments, side gigs, rental income etc)
  • Details of expenses for your self-employed company
  • Pension contributions and tax relief (to get a PDF of all your pension contributions this tax year, please get in touch on our online chat box or through email here and we’ll get this for you in a few minutes)
  • Proof of any income from employment (e.g: a P60 or P45)

How do I do my Self Assessment though?

You have a couple of options.

  1. Online on HMRC’s website - gather all of the information together and submit it online and completely for free.
  2. Use an accountant service - they’ll do it all for you, and there’s no paperwork or stress on your part. We’ve partnered with TaxScouts who’re offering a 10% discount to all Penfold customers, who even give you your own personal accountant! 

What if I need help?

If you need any help with your tax return or submitting your pension contributions, please reach out to our friendly team on our online chat or through email.

Lee Mannion

Lee Mannion