Self Assessment: What Warrington Business Owners Need to Know for 2026

David Parker
17 minutes ago
2 min read

If you’re a sole trader, consultant or company director, Self Assessment is one of those tasks that never quite feels straightforward.

small business owner completed self assessment

Even if you’ve been doing it for years, rules change, thresholds move and it’s easy to miss opportunities to plan better or pay less tax than expected.

This guide explains what Self Assessment really involves in 2026, who needs to file, and how Warrington business owners can avoid common problems.

What Is a Self Assessment Tax Return?

A Self Assessment tax return is how individuals report income to HMRC that isn’t taxed automatically.

You may need to file if you are:

A sole trader or freelancer
A consultant or contractor
A company director
Earning rental income
Receiving dividends or other untaxed income

Even if your income feels “simple”, mistakes or late submissions can lead to penalties, interest and unnecessary stress.

Do I Need to Register for Self Assessment?

You usually need to register if:

You became self-employed
You started earning untaxed income
You’ve never filed before

Registration must be done by 5 October following the end of the tax year in which you started.

HMRC guidance can be found here:👉 https://www.gov.uk/register-for-self-assessment

Key Self Assessment Deadlines for 2026

Missing deadlines is one of the most common issues we see.

31 October 2026 – Paper tax return deadline
31 January 2027 – Online tax return deadline
31 January 2027 – Tax payment due (plus first payment on account, if applicable)
31 July 2027 – Second payment on account (if required)

Planning early makes a significant difference to cash flow.

Common Self Assessment Mistakes We See

Many business owners come to us after running into one of these:

Not setting money aside for tax
Missing allowable expenses
Forgetting additional income streams
Filing late due to last-minute panic
Assuming software alone “takes care of it”

One client recently said:

“Purple Accounts explain everything clearly and always help us plan ahead. We finally feel in control of our tax instead of dreading it.”⭐⭐⭐⭐⭐ Google Review