Capital Allowances for Company Cars on a CT600

TinyTax can file CT600 returns for companies that own a car, including electric and low-emission vehicles. This guide explains how to enter capital allowances for a company car in the Tax Computation section.

Why Cars Are Different

Cars cannot use the Annual Investment Allowance (AIA). Instead, HMRC requires cars to go into capital allowance pools, where a percentage is claimed each year as a Writing Down Allowance (WDA) — or, for qualifying vehicles, a First Year Allowance (FYA) in the year of purchase.

The applicable rate depends on the car's CO2 emissions:

Emission rate	Pool / Allowance
0g/km (zero-emission, purchased new)	100% First Year Allowance (FYA), available for cars purchased up to 31 March 2027 — enter in the Zero-emission cars row
0g/km (zero-emission, second-hand or pool brought forward)	18% WDA — enter in the Main pool row
1–50g/km	18% WDA — enter in the Main pool row
Over 50g/km	6% WDA — enter in the Special rate pool row

ℹ The 100% First Year Allowance for new zero-emission cars was extended to 31 March 2027. Zero-emission cars purchased new on or before that date can still claim 100% FYA. However, for accounting periods starting on or after 1 April 2025, HMRC changed where the allowance appears on the CT600 — it now shows in the Others section (Box 730) rather than Box 726. TinyTax handles this automatically.

How to Enter Car Capital Allowances in TinyTax

You calculate the allowable capital allowance figure yourself (based on the car's CO2 emissions and tax written-down value), then enter it in TinyTax using the Advanced Capital Allowances section.

⚠ Do not enter WDA in the Annual Investment Allowance (AIA) field. The AIA field is for Annual Investment Allowance only — cars must use the Advanced Capital Allowances section described below.

Using Advanced Capital Allowances

In the Tax computation section, find the Capital allowances chevron and click Show ▾ next to that heading
The chevron expands to reveal the Advanced Capital Allowances grid
Find the appropriate pool row:

- Zero-emission cars — for a new zero-emission car where you are claiming the 100% FYA (purchased up to 31 March 2027) - Main pool — for zero-emission cars where FYA has already been claimed in a prior year (ongoing WDA on remaining value); also for cars with 1–50g/km CO2 - Special rate pool — for cars with over 50g/km CO2 (6% WDA)

Enter your WDA claimed or FYA in the field for that row
If there is a balancing charge (from a disposal), enter it in the separate Balancing charge field

⚠ Enter WDA claimed and balancing charge in separate fields — do not net them together. HMRC requires these reported separately.

The advanced section routes amounts to the correct CT600 boxes and the deduction flows through to reduce your taxable profit and corporation tax.

What TinyTax Does Not Calculate Automatically

TinyTax does not maintain a running capital allowance pool or automatically calculate WDA percentages. You need to:

Track the tax written-down value of the car each year
Calculate the WDA (or FYA) for the period yourself
Enter the figure in TinyTax

If you are unsure of the correct allowance to claim, an accountant or HMRC's capital allowances guidance at gov.uk/capital-allowances can help.

Zero-Emission Cars: Box 726 and Box 727

For periods starting before 1 April 2025, zero-emission car capital allowances appeared in Box 726 and balancing charges in Box 727 on the CT600.

For periods starting on or after 1 April 2025, HMRC changed the CT600 schema: the ZeroEmissionsCars section (Box 726/727) is no longer used. Instead, those amounts are reported in the Others section:

Amount type	CT600 box (periods before April 2025)	CT600 box (periods from April 2025)
ZEC capital allowances (FYA)	Box 726	Box 730 (Others)
ZEC balancing charges	Box 727	Box 725 (Others)

You do not need to change how you enter figures in TinyTax. Always use the Zero-emission cars row for zero-emission car entries. TinyTax automatically re-routes the amounts to the correct CT600 box based on your period start date. If Box 726 or Box 727 appear empty on your CT600 draft for a period starting from April 2025, that is expected — your figures are in Box 725 or Box 730 instead.

How Allowances and Charges Appear on the CT600 Draft

Each pool type has two CT600 boxes: one for balancing charges (adds to profit) and one for capital allowances (reduces profit).

Pool	Balancing Charges box	Capital Allowances box
Special rate pool	Box 695	Box 700
Main pool	Box 705	Box 710
Zero-emission cars (periods before April 2025)	Box 727	Box 726
Others (incl. ZEC re-routed from April 2025)	Box 725	Box 730

ℹ If your draft CT600 shows your WDA or FYA amount in Box 710 or Box 730, that is correct — those are the Capital Allowances columns. Box 725/705/695 are Balancing Charges and only appear when you have a disposal gain.

Example — Zero-Emission Car FYA (period starting April 2025 or later)

New electric car purchased in January 2026 for £35,000. Claiming 100% FYA.

Using the Advanced Capital Allowances section:

Open the Capital allowances chevron
Find the Zero-emission cars row
Enter FYA: £35,000
On the draft CT600, this appears in Box 730 (Others — Capital Allowances), not Box 726

Example — Car with 18% WDA (1–50g/km CO2)

Pool brought forward: £20,000. 18% WDA = £3,600.

Using the Advanced Capital Allowances section:

Open the Capital allowances chevron
Find the Main pool row
Enter WDA claimed: £3,600
On the draft CT600, this appears in box 710 (Capital Allowances column)

Example — Expensive Car (>50g/km CO2)

Pool brought forward: £79,500. 6% WDA = £4,770. Separately, an older car was sold at a gain giving a balancing charge of £64.

Using the Advanced Capital Allowances section:

Find the Special rate pool row
WDA claimed: £4,770
Balancing charge: £64
Net tax deduction: £4,770 − £64 = £4,706

Common Questions

Can I use TinyTax if my company has a company car?

Yes. Enter the capital allowance amount as described above. TinyTax is a full CT600 filing solution for companies with company cars.

Why is Box 727 empty on my CT600?

For periods starting on or after 1 April 2025, HMRC no longer accepts entries in Box 727 (zero-emission cars — balancing charges). Any balancing charge you entered in the Zero-emission cars row is automatically re-routed to Box 725 (Others — Balancing Charges). The figure is still there and correct — just in a different box than earlier periods.

Does the car need to be declared anywhere else in the return?

The capital allowance appears in your Tax Computations document. For the CT600 itself, the deduction flows through to your taxable profit figure. If the car is a benefit in kind for a director or employee, that is a payroll (P11D) matter separate from the CT600 — TinyTax does not handle P11D filings.

Why does HMRC say I need commercial software?

HMRC's own free Corporation Tax filing service closed on 31 March 2026. All companies now need to use commercial software like TinyTax to submit CT600 returns electronically.

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