[ Self Assessment Tax Returns ]
Self Assessment Tax Returns London
If you're a sole trader, subcontractor or landlord in London, your self assessment return is the one filing you can't afford to get wrong. We prepare and file your return, reclaim any over-deducted CIS tax, and make sure you're using every allowable expense.
[ Self Assessment Tax Returns ]
Don't want the hassle of doing your own tax return?
LCA Limited can prepare and submit your Self Assessment tax return.
- Self Assessment
- CIS tax returns
- Tax calculations
- Self-employed accounts
- Construction accountants
[ Free Tax Check ]
Get my free tax check
Filing
Prepared and filed on deadline
CIS reclaim
Over-deducted tax recovered
Expenses
Every allowable claim made
NIC
Class 4 NIC calculated correctly
Self assessment is how sole traders, subcontractors, partners, landlords and company directors report income that is not fully taxed through PAYE. The online filing deadline is 31 January each year, and the paper deadline is 31 October. Miss it and HMRC issues an automatic £100 penalty — even if you owe no tax or are due a refund.
For construction workers, the biggest opportunity in self assessment is reclaiming over-deducted CIS tax. If you are a subcontractor who has had 20% or 30% deducted from your pay throughout the year, those deductions are advance payments towards your tax bill — not a final charge. When we file your self assessment, the total CIS deducted is set against your actual income tax and Class 4 NIC liability, and any excess is refunded to you by HMRC. Many subcontractors are owed thousands of pounds and never claim it because they do not file.
We also make sure every allowable expense is claimed — materials, tools, vehicle costs (either actual costs or 45p per mile), workwear and PPE, phone and admin costs, and more. And we handle the payments on account calculation, which catches many first-time filers off guard when their bill is effectively 150% of what they expected.
[ What We Handle ]
Self Assessment Tax Returns London — the full scope.
- ◢Self assessment tax return preparation and filing
- ◢CIS over-deduction reclaims for subcontractors
- ◢Allowable expenses and capital allowances
- ◢Class 2 and Class 4 NIC calculations
- ◢Partnership and multiple-income-source returns
- ◢Payments on account planning and review
[ Frequently Asked Questions ]
Self Assessment Tax Returns London — your questions answered.
Who needs to file a self assessment tax return?
You must file a self assessment return if you are self-employed and earned more than £1,000, a partner in a business, a CIS subcontractor who had tax deducted, a company director with income not fully taxed through PAYE, a landlord with rental income, or anyone with income over £100,000. If HMRC has asked you to file, you must — even if you believe you owe nothing.
When is the self assessment deadline?
The online filing and payment deadline is 31 January each year. The paper filing deadline is 31 October. If you miss the deadline, HMRC issues an automatic £100 penalty — even if you owe no tax or are owed a refund. Further penalties of £10 per day apply after three months, and additional percentage-based penalties apply after six and twelve months.
How do I reclaim over-deducted CIS tax?
CIS deductions are advance payments towards your tax bill, not a final charge. You reclaim over-deducted tax by filing a self assessment return — the total CIS deducted across the year is set against your actual income tax and Class 4 NIC, and any excess is refunded by HMRC. You need your CIS deduction statements from every contractor to prove what was deducted.
What expenses can construction workers claim on self assessment?
Sole traders and subcontractors can claim materials, tools, vehicle costs (45p per mile for the first 10,000 miles or actual running costs), workwear and PPE, phone and admin costs, training related to your current trade, and bank and finance charges. Keep receipts for everything — HMRC can ask for them up to six years after the tax year.
What are payments on account?
If your self assessment tax bill is over £1,000 and less than 80% of your income is taxed at source, HMRC requires payments on account — advance payments towards the following year's tax. On 31 January you pay your balancing payment plus half of next year's estimated tax, and the second half is due on 31 July. This can make your January bill 150% of what you expected if you are not prepared.
Ready to talk to a specialist?
Book a free financial site review and we'll review your CIS, tax and accounts — no obligation.