Last updated: 14 October 2026
Can you still claim capital allowances in accounts to 31 December 2006?
Not now. The time limits for claiming or amending capital allowances for a period ending in 2006 expired many years ago, so a claim for that year can’t be made today. But unclaimed spending isn’t always lost: if you still own the asset and never claimed allowances on it, you can usually add it to your pool in a later period that is still open, and claim writing-down allowances from then on. This page explains the old rules briefly and what to do now.
What applied in 2006
In 2006, the Annual Investment Allowance didn’t exist (it started in April 2008). Small and medium-sized businesses could claim first-year allowances on most plant and machinery, typically 40% (or 50% for small businesses in some years), with the balance going into a pool. The main pool writing-down allowance was 25% a year. Those rates no longer apply.
Rules for 2026/27
| Allowance | Rate or limit |
| Annual Investment Allowance | 100% of spending up to £1 million a year |
| Full expensing (companies, new main-pool plant) | 100%, no limit |
| 50% first-year allowance (companies, special rate assets) | 50% |
| Main pool writing-down allowance | 14% from April 2026 |
| Special rate pool | 6% |
| Zero-emission cars | 100% first-year allowance, to April 2027 |
| Structures and buildings allowance | 3% a year |
Time limits now
- Sole traders and partnerships: claims are made on the tax return, which can be amended within 12 months of the 31 January filing date.
- Companies: claims can be made, varied or withdrawn up to the later of 12 months after the filing date of the return, or within the enquiry window.
Claiming on assets you forgot
If you bought equipment years ago, still use it in the business, and never claimed allowances, you can bring it into the pool in the first open period. The value you add is the original cost, not today’s value. AIA isn’t available, because that must be claimed for the period of purchase, but writing-down allowances are.
Example
A plumber bought a van for £18,000 in 2019 and never claimed allowances. In 2026/27, the van is still used in the business. He adds £18,000 to his main pool and claims 14%, which is £2,520, and continues to claim on the reducing balance each year. He can’t go back to 2019 to claim the AIA.
Records to keep
- Purchase invoices and proof of payment
- An asset register with dates and costs
- Evidence that the asset is still used in the business
Why you should check old asset lists
Many small businesses buy tools, computers and furniture without claiming allowances on them, especially in the years before they took on an accountant. A review of the asset register often turns up unclaimed items that can still be added to the pool.
Frequently asked questions
Can I amend a 2006 tax return?
No, those amendment windows closed long ago.
Is overpayment relief an option?
Generally not for capital allowances, because they must be claimed on a return.
Do I need the original invoice?
It’s strongly advised; HMRC may ask for evidence.
What if I sold the asset?
A disposal value goes into the pool and can create a balancing charge.
Related: AIA for sole traders, capital allowance pools until April 2010 and allowances on fixtures.
Talk to Accotax
Want this handled for you? Our team at Accotax can help with claiming capital allowances. See our small business accountants service, or contact us for a free, no-obligation quote.
This page is general guidance based on HMRC rules for the 2026/27 tax year, checked against gov.uk on 14 October 2026. It is not personal advice, so speak to an accountant about your own situation.
