Self Assessment

If your income isn’t taxed at source, such as if you’re a sole trader, landlord, company director, or earn from dividends, capital gains, or overseas sources, you’ll usually need to file a Self Assessment return.

The Self Assessment deadline is 31 January each year for filing your return and paying any tax owed for the previous tax year (which runs from 6 April to 5 April).

If you miss the Self Assessment deadline, HMRC will usually charge an automatic £100 late filing penalty, even if you have no tax to pay. Additional fines and interest can build up the longer it remains unfiled or unpaid.

Yes, you can file your own Self Assessment through HMRC’s online system. However, many people choose to use an accountant to save time, avoid mistakes, and ensure they’re claiming every allowance and expense they’re entitled to.

To file your Self Assessment, you’ll need details of all your income and expenses for the tax year. This typically includes:

• Employment income (P60 or P45 forms, and any P11D for benefits)

• Self-employment records (invoices, receipts, and business expenses)

• Bank interest and dividends

• Rental income and property expenses

• Pension contributions and gift aid donations

• Capital gains or overseas income

Having organised records makes filing quicker, more accurate, and helps ensure you don’t miss out on any tax reliefs.

You’ll need to register for Self Assessment if you receive income that isn’t taxed at source, such as self-employment earnings, rental income, dividends, or capital gains. Registration is done through HMRC, and you should complete it by 5 October following the end of the tax year in which you earned the income.

Yes, if you’re self-employed, you can claim allowable business expenses on your Self Assessment to reduce your taxable profit. These can include:

• Office costs such as phone bills, software, and stationery

• Travel and vehicle expenses

• Marketing and advertising costs

• Professional fees, including accountants and insurance

• Premises costs like rent, utilities, or equipment

Only expenses that are wholly and exclusively for business purposes can be claimed, so it’s important to keep accurate records and receipts.

The SA100 Form is what's used for the Self Assessment Tax Return - which is HMRC’s way of finding out how much Income Tax and National Insurance you need to pay on any income which isn’t taxed at source.

Starting from April 2024, Making Tax Digital for Income Tax Self Assessment (MTD ITSA) will be implemented, requiring digital reporting for sole traders and landlords with income exceeding £10,000.

If you’re self-employed or earning income from your own business, you’ll need to register as a sole trader with HMRC before your first Self Assessment.

This isn’t the same as setting up a limited company - it’s simply letting HMRC know you’re self-employed so they can issue a Unique Taxpayer Reference (UTR). Once registered, you’ll file your annual Self Assessment to report your income and expenses.

Yes - if two or more people are running a business together, the partnership must register with HMRC so it can file a Partnership Tax Return (SA800). Each partner will also need to file their own Self Assessment to declare their share of the profits.