A Simple Guide to Self Assessment

Self Assessment is how HMRC collects tax from individuals whose income isn’t taxed automatically through PAYE.

This guide is for sole traders, landlords, company directors and anyone with untaxed income who wants a clear overview of what’s involved, without technical language or guesswork.

Self Assessment is how HMRC collects tax from individuals whose income isn’t taxed automatically through PAYE.

This guide is for sole traders, landlords, company directors and anyone with untaxed income who wants a clear overview of what’s involved, without technical language or guesswork.

Who Needs to File a Self Assessment Return

You’ll usually need to file a Self Assessment return if you receive income outside of standard employment. This commonly includes:

  • Self-employed individuals and sole traders
  • Company directors
  • Landlords receiving rental income
  • Individuals with additional income such as dividends or investments

If HMRC needs a return from you, they’ll expect all relevant income to be reported accurately.

What Income Is Included

A Self Assessment return brings together all taxable income for the year, including:

  • Trading or self-employment income
  • Rental income
  • Dividends
  • Savings and investment income
  • Other taxable income

Including everything correctly helps avoid delays, queries or amendments later on.

Key Deadlines to Be Aware Of

Self Assessment works to annual deadlines, including:

  • Registering for Self Assessment (if you’re new)
  • Submitting your tax return
  • Paying any tax owed

Planning ahead makes these deadlines far easier to manage and avoids unnecessary pressure.

What Information You’ll Need

To prepare your return, you’ll usually need:

  • Records of income received
  • Details of business or rental expenses
  • Bank statements
  • P60s or P45s (if applicable)
  • Previous tax returns

Keeping records organised throughout the year can save time and stress later.

Common Mistakes to Watch Out For

Some of the most common issues we see include:

  • Forgetting to include all sources of income
  • Claiming expenses that aren’t allowable
  • Filing late
  • Not budgeting for tax payments

Most of these are avoidable with the right preparation and support.

How We Can Help

We help clients prepare accurate Self Assessment returns, deal with HMRC queries and plan ahead so there are no surprises.

If you’d like support with your tax return, you can find out more about our Personal Tax services by contacting us.