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Capital Allowances

Posted by David Patterson 26 Jan 2026 at 18:27
Hi, Where do I enter Capital Allowances on the tax computation !! (I want to claim 100% 1st year allowances on a EV purchase but can't see an option for capital allowances!)

I can see a box for any annual investment allowances, but nothing for capital allowances ? Do I just enter it as a negative number in the Other Adjustments box under trading income ?

3 Comments

T
Tim Fouracre Staff 26 Jan 2026 at 18:33
or your 100% first year allowance on the EV purchase, you should use the Annual Investment Allowance (AIA) field in the tax computation section.

The AIA field might be hidden if you haven't entered any capital allowances yet. To reveal it:

1. Scroll down to the Tax Computation section

2. Click "Show all" (link at the top right of that section)

3. You'll see "Less: Annual Investment Allowance" (Box 735)

4. Enter the full cost of your EV there

The AIA gives 100% tax relief in the year of purchase, which achieves the same result as the 100% First Year Allowance. The £1 million AIA limit is more than sufficient for electric vehicles.

You don't need to use the "Other Adjustments" field - the AIA field is the correct place for this.

Let me know if you have any trouble finding it.
D
David Patterson 27 Jan 2026 at 11:49
Thanks Tim, I can see it and entering the value gets the correct CT figure I was expecting. However, I'm pretty sure it needs to be in Box 726 - Zero Emission Cars and not 735 AIA ?
I can't see any of the Capital Allowance box's at all, like 705 - Machinery and Plant main pool?
Is there a way of getting a more comprehensive list of box's for the CT600 entry as it's pretty limited even if I hit the unhide button?

Thanks a lot
David
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Tim Fouracre Staff 27 Jan 2026 at 14:27
You're right that technically Zero Emission Cars should go in Box 726 rather than Box 735 (AIA). Both give 100% relief in the year of purchase, so your CT figure will be correct either way.

TinyTax currently uses a simplified approach - we have AIA (Box 735) as a catch-all for 100% capital allowances, but we don't yet have the full breakdown of capital allowance pools (Box 705 main pool, Box 726 ZEVs, etc.).

For most small companies claiming 100% relief via AIA, this works fine. But you're right that for a more detailed CT600 with separate capital allowance categories, we're limited at the moment.

If the correct categorisation in Box 726 is important to you (e.g. for your records or if AIA has been used elsewhere), you may need to file via HMRC's own service or commercial software that supports the full capital allowances schedule.