CT600 Box 315: Capital Allowances Explained

Capital allowances let you deduct the cost of business assets from your taxable profits. Box 315 is where these allowances are reported on your CT600.

What is Box 315?

Box 315 on the CT600 is typically labelled "Balancing charges" - but the capital allowances section includes multiple boxes (315-340) for different aspects of capital allowances.

The key capital allowances boxes are:

Box	Description
315	Balancing charges
690	Annual Investment Allowance (AIA) claimed
700-735	Pool allowances

Box 315 specifically handles balancing charges (when you sell assets for more than their tax value).

What Are Capital Allowances?

Capital allowances replace depreciation in your tax calculation:

Accounting: You depreciate assets over their useful life
Tax: You claim capital allowances instead

Depreciation is added back to profits, and capital allowances are deducted. This is a key tax adjustment.

Types of Capital Allowances

Annual Investment Allowance (AIA)

The main relief for most businesses:

100% deduction in year of purchase
Current limit: £1,000,000 per year
Most plant and machinery qualifies
Cars do NOT qualify

Writing Down Allowance (WDA)

For assets not covered by AIA or exceeding the limit:

Pool Type	Rate	Assets Included
Main pool	18%	Most equipment
Special rate pool	6%	Integral features, long-life assets

First Year Allowances (FYA)

100% allowance for specific assets:

Electric vehicles (100%)
Zero-emission goods vehicles
Energy-efficient equipment

Balancing Allowances and Charges

When you sell an asset:

Balancing allowance: Sale proceeds less than tax value (further relief)
Balancing charge (Box 315): Sale proceeds exceed tax value (taxable)

How Capital Allowances Work

Example: Buying Equipment

Purchase:

Equipment cost: £50,000
Claim AIA: £50,000 (100%)
Tax relief: £50,000 × 25% = £12,500 saved

No Box 315 entry needed - this is a straightforward AIA claim.

Example: Selling Equipment

Sale:

Original cost: £50,000
AIA claimed: £50,000
Tax value: £0
Sale price: £15,000

Box 315: £15,000 (balancing charge - added to profits)

You claimed relief on £50,000 but only lost £35,000 (cost minus sale price), so £15,000 comes back into profits.

Calculating Capital Allowances

Step 1: Identify Qualifying Expenditure

Assets that qualify for capital allowances:

Qualifies:

Computers and IT equipment
Office furniture
Machinery and tools
Commercial vehicles
Equipment for trade

Does NOT qualify:

Land and buildings (different rules)
Cars (limited allowances)
Assets for non-business use

Step 2: Claim AIA First

Up to £1,000,000 can be claimed as AIA:

``` Equipment purchased £80,000 AIA claimed £80,000 Remaining for pool £0 ```

Step 3: Calculate Pool Allowances

For amounts exceeding AIA:

``` Pool brought forward £20,000 Additions (no AIA) £10,000 Total £30,000 WDA at 18% £5,400 Pool carried forward £24,600 ```

Step 4: Handle Disposals

When you sell assets:

``` Pool before disposal £24,600 Sale proceeds £30,000 Excess (balancing charge) £5,400 ← Box 315 ```

Box 315 Specifically

Box 315 is for balancing charges only:

Enter in Box 315 when:

You sell an asset for more than its tax value
Your main pool goes negative
You dispose of a single asset pool at a gain

Amount to enter:

The excess of sale proceeds over the pool value
This amount is added to your taxable profits

Capital Allowances for Cars

Cars have special rules:

CO2 Emissions	Treatment
0g/km (electric)	100% FYA
1-50g/km	Main pool (18% WDA)
Over 50g/km	Special rate pool (6% WDA)

Cars never qualify for AIA.

Car Example

Purchase: £30,000 petrol car (120g/km CO2):

Pool: Special rate (6%)
Year 1 allowance: £30,000 × 6% = £1,800
Pool carried forward: £28,200

Sale after 3 years for £15,000:

Pool value: ~£24,900
Sale proceeds: £15,000
Balancing allowance: £9,900 (extra relief)

Private Use Adjustment

If assets have personal use:

``` Equipment cost £10,000 AIA (full) £10,000 Private use: 20% £2,000 Net allowance £8,000 ```

The private use portion is added back.

Common Mistakes

1. Claiming AIA on Cars

Wrong: £25,000 car in AIA claim Right: Cars go to main or special rate pool

2. Exceeding the AIA Limit

Wrong: Claiming £1,200,000 AIA Right: Maximum is £1,000,000 (pro-rated for short periods)

3. Missing Balancing Charges

Wrong: Not reporting Box 315 when selling assets Right: Calculate and include any balancing charges

4. Wrong Pool Rates

Wrong: Using 18% for integral features Right: Integral features use 6% special rate pool

When Using TinyTax

TinyTax handles capital allowances by:

Tracking your capital allowances pools
Calculating AIA and WDA automatically
Warning if you exceed limits
Computing balancing charges on disposals
Populating all relevant boxes correctly

Need Help?

Capital allowances can significantly reduce your tax bill. TinyTax calculates your allowances and ensures they're correctly claimed on your CT600.

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