What Are Writing Down Allowance Rates for Dental Practices?
Writing down allowance rates determine how quickly you can claim tax relief on the cost of plant and machinery used in your dental practice. When you buy equipment such as a dental chair, an OPG X-ray machine, or a compressor, you cannot deduct the full cost from your profits in one year (unless you use the Annual Investment Allowance). Instead, the cost enters a "pool" and you claim a percentage of the remaining value each year. That percentage is the writing down allowance rate.
From April 2026, the main rate of writing down allowance for general pool assets changed from 18% to 14% for corporation tax (1 April 2026) and income tax (6 April 2026) [1]. The special rate pool remains at 6% for now, but will reduce to 4% from 1 April 2026 for corporation tax purposes [2]. These changes directly affect how much tax relief you can claim each year on your dental practice equipment.
This guide covers the rates, which assets go in which pool, and how to structure your claims for maximum benefit. It is written for UK dentists, associates, and practice owners who need practical, grounded advice.
How Writing Down Allowances Work
Writing down allowances apply to the cost of plant and machinery that does not qualify for another allowance, or when there is value remaining after claiming the maximum amount of another allowance such as the Annual Investment Allowance (AIA) [3]. The AIA remains at £1 million for 2026/27, so most dental practices will use that first for new equipment [2].
Once you have claimed AIA on qualifying expenditure, any remaining balance in the pool attracts writing down allowances at the appropriate rate. The same applies if you buy second-hand equipment where the seller has already claimed capital allowances and you have made a joint election under section 198 of the Capital Allowances Act 2001.
Each year, you calculate the writing down allowance on the pool balance at the end of your accounting period. The allowance reduces the pool value, and you claim that amount against your taxable profits. The process repeats each year until the pool is fully relieved or the asset is sold.
Main Pool vs Special Rate Pool
Most dental practice equipment goes into the main pool. This includes dental chairs, X-ray machines (including OPGs), autoclaves, suction units, compressors, lights, computers, and surgery furniture. The main pool rate is 14% from April 2026, down from 18% [1].
The special rate pool applies to integral features of a building and long-life assets. Integral features include electrical systems, water systems, heating and ventilation, lifts, and external solar shading. Long-life assets are those with an expected useful economic life of 25 years or more, where the cost of all such items bought in an accounting period exceeds £100,000 [1].
If the value of long-life items totals £100,000 or less in an accounting period, you can put them in the main rate pool instead [1]. This is a useful planning point for dental practices buying multiple high-value items.
Writing Down Allowance Rates from April 2026
The table below summarises the current and upcoming rates:
- Main pool (general plant and machinery): 14% from April 2026 (was 18% before) [1]
- Special rate pool (integral features, long-life assets): 6% from April 2026, reducing to 4% from 1 April 2026 for corporation tax [2]
- Structures and Buildings Allowance (SBA): 3% per year on qualifying construction or renovation costs of non-residential buildings [1]
- Annual Investment Allowance: £1 million for 2026/27 [2]
- First-year allowance for zero-emission cars and goods vehicles: 100% for 2026/27 [2]
Note that the special rate pool reduction to 4% applies to corporation tax from 1 April 2026. For income tax purposes (sole traders and partnerships), the rate remains at 6% for 2026/27 unless further legislation is introduced [1][2].
Worked Example: Dental Practice Equipment Purchase
Dr Patel owns a single-handed NHS and private practice. In the 2026/27 tax year, she buys the following new equipment:
- Dental chair: £18,000
- OPG X-ray machine: £22,000
- Autoclave: £6,000
- Compressor: £4,500
- Total: £50,500
Dr Patel claims the Annual Investment Allowance on the full £50,500, so no balance remains to attract writing down allowances in year one. If she had already used her AIA on other expenditure, or if the total exceeded £1 million, the excess would enter the main pool and attract writing down allowances at 14%.
Now suppose Dr Patel buys a second-hand dental chair for £15,000 from a retiring dentist. The seller has already claimed capital allowances, and they make a section 198 election. The £15,000 enters Dr Patel's main pool. She cannot claim AIA on second-hand assets where a section 198 election applies (the election transfers the seller's pool balance instead). In year one, she claims writing down allowances of 14% on the pool balance: £15,000 x 14% = £2,100. The remaining £12,900 carries forward to the next year.
Which Dental Assets Go in Which Pool?
Main Pool (14% rate)
- Dental chairs and units
- X-ray machines (intraoral, OPG, CBCT)
- Autoclaves and sterilisation equipment
- Compressors and suction units
- Surgery lights and cabinetry (if not integral to the building)
- Computers, monitors, and practice management software (if capitalised)
- Dental loupes and microscopes (if used for treatment)
- Handpieces and instruments (if capitalised rather than expensed)
Special Rate Pool (6% rate, reducing to 4%)
- Electrical systems (rewiring, distribution boards)
- Water and drainage systems
- Heating and air conditioning
- Ventilation systems
- Lifts and hoists
- External solar shading
- Long-life assets (expected life 25+ years, total cost over £100,000)
Structures and Buildings Allowance (3% rate)
- Cost of constructing a new practice building
- Cost of buying a practice building (post-29 October 2018)
- Renovation or conversion costs for non-residential buildings
If you are unsure whether an asset qualifies as plant and machinery or as a building structure, consult a dental-specialist accountant. HMRC has detailed guidance in its Capital Allowances Manual, and the distinction can be technical.
Planning Points for Dental Practices
Use AIA First
The AIA at £1 million means most dental practices can claim 100% relief on new equipment in the year of purchase. Writing down allowances only become relevant when you have exhausted the AIA or when buying second-hand assets with a section 198 election. Plan your equipment purchases to maximise AIA usage across accounting periods.
Consider Timing of Purchases
If you are close to your year end, buying equipment before that date brings the AIA claim into the current year. Delaying the purchase by a few days pushes the relief into the next period. This matters if your profits are higher in one year than another.
Separate Integral Features from General Equipment
When you buy a practice building or carry out a renovation, the cost of integral features (electrics, plumbing, heating) goes into the special rate pool at 6%. The cost of general plant and machinery (chairs, X-rays) goes into the main pool at 14%. A proper capital allowances survey can identify all qualifying items and ensure you claim the correct rate for each.
Review Your Pool Balances Annually
If you have old pool balances from previous years, check whether you are still claiming writing down allowances on them. Many practices forget to claim on small pool balances, leaving tax relief unclaimed. A pool balance below £1,000 can be claimed in full as a small pools allowance.
Common Mistakes with Writing Down Allowance Rates
Mistake 1: Assuming all equipment goes in the main pool. Integral features and long-life assets go in the special rate pool. If you put a new heating system in the main pool at 14%, HMRC can challenge the claim and restrict relief to 6%.
Mistake 2: Ignoring the section 198 election. When buying a practice with existing fixtures, you and the seller must make a joint election within two years of the purchase. Without it, the buyer cannot claim capital allowances on those fixtures. This is a common oversight in dental practice acquisitions.
Mistake 3: Claiming writing down allowances on buildings. The cost of the building itself (bricks and mortar) does not qualify for plant and machinery allowances. Only the fixtures and integral features inside it qualify. The Structures and Buildings Allowance at 3% applies to the building cost, but that is a separate relief.
Mistake 4: Not claiming on second-hand equipment. Second-hand dental chairs, X-ray machines, and other equipment still qualify for writing down allowances, provided the seller has not already claimed 100% relief and you make the correct election.
How Writing Down Allowances Interact with Practice Sale
When you sell a dental practice, the capital allowances pool balances affect the gain calculation. If you have claimed writing down allowances on equipment, the tax written-down value is lower than the original cost. On sale, any proceeds up to the original cost are deducted from the pool. If proceeds exceed the original cost, the excess is a balancing charge (taxed as income).
For goodwill, the position is different. Goodwill amortisation in company accounts attracts tax relief at 6.5% per year for qualifying goodwill acquired post-1 April 2019. Goodwill purchased between 8 July 2015 and 31 March 2019 generally has no tax relief. Writing down allowances do not apply to goodwill.
If you are planning to sell your practice, review your capital allowances pool balances with a dental-specialist accountant. The interaction between pool balances, balancing charges, and the sale price can significantly affect your net proceeds.
Practical Steps for Dental Practice Owners
- List all plant and machinery in your practice, including purchase dates and costs.
- Separate main pool assets from special rate pool assets and building costs.
- Check your AIA usage for the current and previous accounting periods.
- Review old pool balances to ensure you are claiming writing down allowances each year.
- Get a capital allowances survey if you have bought or renovated a practice building since 2018.
- Consult a dental-specialist accountant before making significant equipment purchases or selling the practice.
For more detailed guidance on practice accounting and capital allowances, see our practice accounting services page. If you are an associate considering buying equipment, our for associates page covers the specific tax implications.
Frequently Asked Questions
Can I claim writing down allowances on a dental chair I bought five years ago?
Yes, if you have not already claimed capital allowances on it. The chair should have entered your main pool in the year of purchase. If you missed the claim, you can amend your tax return for the relevant year (within the time limits) or claim the remaining pool balance going forward.
What happens to writing down allowances when I sell a dental chair?
The sale proceeds (up to the original cost) are deducted from the main pool. If the pool balance becomes negative, a balancing charge arises and is added to your taxable profits. If the pool balance remains positive, you continue claiming writing down allowances on the reduced balance.
Do writing down allowance rates apply to cars used in my dental practice?
Yes, but cars have their own rules. Cars with CO2 emissions above 50g/km go into the main pool (14% rate) or special rate pool (6% rate) depending on emissions. Zero-emission cars qualify for a 100% first-year allowance. Cars are not eligible for the AIA.
Can I claim writing down allowances on practice software?
Software that you buy outright (not subscription-based) and capitalise as a fixed asset qualifies for writing down allowances. It goes into the main pool at 14%. Subscription-based software is typically expensed as a revenue cost and does not enter the capital allowances pool.
For a full review of your practice's capital allowances position, speak to a dental-specialist accountant. Contact our team at Dental Finance Partners for a free initial discussion.