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100% First Year Allowance
I believe "100% First Year Allowance" was very recently added to tax return. Maybe there is a bug in this new field?
I entered EV cost to FYA and entered Equipment cost to AIA. The form calculated Tax correctly (deducting FYA and AIA from Profits). Submitted CT600 to HMRC yesterday and noticed today that tax more than doubled :(
It appears that FYA is missing completely in CT600 form (Calculated tax = 25K); Annual Account form has correct Tax (10K) and Tax Computations has Tax = 0.
I haven't overwitten tax manually. What am I doing wrong?
I entered EV cost to FYA and entered Equipment cost to AIA. The form calculated Tax correctly (deducting FYA and AIA from Profits). Submitted CT600 to HMRC yesterday and noticed today that tax more than doubled :(
It appears that FYA is missing completely in CT600 form (Calculated tax = 25K); Annual Account form has correct Tax (10K) and Tax Computations has Tax = 0.
I haven't overwitten tax manually. What am I doing wrong?
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Apologies for the delay. We have now deployed a fix for the issue that was preventing your advanced capital allowances from flowing through correctly into the amendment flow.
To get this corrected:
1. From your dashboard, click File Amendment on the accepted return for Inteligate Ltd for the year ended 31 March 2026.
2. Start a fresh amendment rather than reusing the earlier ones you created.
3. Go through Review & Submit and regenerate the preview, but do not click Submit yet.
4. Reply on this thread once you have done that, and we will verify the corrected figures before you press Submit.
Best regards,
Tim
I created new Amendment (not submitted yet) and the findings are:
- CT600: Field 440 - Tax is correctly calculated
- CT600: Field 155 - Profit is correctly calculated
- CT600: Expenses (FYA) are not shown anywhere. Is that correct? Shouldn't that be included somewhere - eg. Field 726, Field 688, others??
- Corporation Tax Computations: FYA is missing. "Profit before Tax" and "Net trading profits" are correct but Expenses between these two numbers do not explain full amount that was deducted.
- Input form: numbers entered in some of the news fields do not change Tax Payable. I need to enter FYA (nothing happens), then modify some other field (eg. other adjustments) and undo the modification.
I believe you have access to my tax computation so hopefully you will be able to see what goes wrong.
Many thanks Tim!!
Thank you for the careful verification — you were right. Your CT600 total tax was correctly calculated, but the £53,080 FYA was missing from the computations document because our document generator was not receiving the pool data alongside the calculation.
We have now deployed a fix. When you next regenerate your amendment preview, the computations iXBRL and PDF should both show the zero-emission cars FYA row explaining the £53,080 deduction.
Please:
1. From your dashboard, open your amendment for Inteligate Ltd for the year ended 31 March 2026.
2. Regenerate the preview.
3. Reply on this thread and we will verify the updated computations before you press Submit.
On the form reactivity issue you flagged — entering FYA not updating Tax Payable until another field is touched — that is a separate client-side issue we have not addressed in this fix. If the displayed tax figure ever looks stale, touching another field (as you discovered) forces a refresh. Not a blocker for submission since the server-side calculation is authoritative.
Best regards,
Tim
It looks better now but there is still an error. The form to input the numbers says:
"Zero-emission cars 100% First Year Allowance on new zero-emission cars. Boxes 726/727."
But the number went to box 695 on CT600 instead.
As per the form the field 695 should be filled with: "Special rate pool 6% WDA on integral features, long-life assets, cars >50 g/km CO2. Boxes 695/700."
Two updates.
First, a scheduled cleanup job on our side misclassified your active amendment sessions as "duplicates" and hid them at 19:15 UK time today, 22 April 2026. That was a bug in our cleanup logic, not anything you did. I have deployed a fix and restored your amendment sessions.
Second, your most recent amendment session (the one you regenerated around 17:45) was saved with the capital allowance draft as "Special rate pool / WDA" rather than "Zero-emission cars / FYA", which is why the £53,080 appeared in box 695. Please ignore that amendment session. An earlier restored amendment session still holds the "Zero-emission cars / FYA £53,080" draft state.
Please do not submit yet. We are now checking the correct CT600 treatment for zero-emission car allowances for periods starting on or after 1 April 2025, because the HMRC schema changed at that cutover and box 726 behaves differently after that date. We will come back to you shortly with the next step.
Best regards,
Tim
Regarding duplicates - I did notice that everytime I amend CT600 it creates a new version. The counter keeps increasing #1, #2,...#9. I cannot seem to pick up work where I left it; instead it always starts with numbers submitted. Or maybe I do something wrong.
Thanks for your patience — we're still finalising the correct CT600 treatment for your ZEC FYA for periods starting on or after 1 April 2025. I'll reply here as soon as we have a clear answer. You don't need to do anything in the meantime.
On the amendment numbering — you're not doing anything wrong. Right now, clicking "Amend CT600" creates a fresh session each time rather than picking up an in-progress one, and the dashboard doesn't yet expose a way to resume an existing amendment. That's a product gap on our side, not a mistake on yours. I've logged it for improvement. For your specific case there's nothing you need to do — the draft carrying your Zero-emission cars £53,080 FYA is already saved against an earlier amendment session, and we'll steer you to the right one when we come back with the schema answer.
Best regards,
Tim
Good news — your schema question is resolved and we have deployed a fix.
HMRC's guidance for the Corporation Tax online service (updated 16 April 2026) confirms the 100% first-year allowance for zero-emission cars has been extended to 31 March 2027. For accounting periods starting on or after 1 April 2025, the claim goes into the "Other allowances and charges" bucket (box 725 on the CT600), not the zero-emission cars box (726) — the schema rule prevents 726 for those periods. Your £53,080 is still fully claimable; only the reporting box has moved.
The fix we shipped this afternoon handles that routing automatically. You keep entering the claim under Zero-emission cars 100% FYA in our form (where it semantically belongs for your books), and we re-route it to box 725 on the submitted envelope. No change for you in the form.
Please:
1. From your dashboard, open Amendment #6 on Inteligate Ltd for the year ended 31 March 2026 (the session created around 16:11 on 22 April that has the correct Zero-emission cars 100% FYA £53,080 draft).
2. Go through Review & Submit and regenerate the preview.
3. Reply on this thread once you have regenerated, and we will verify the £53,080 is landing correctly in box 725 before you press Submit.
Please ignore the later amendment sessions (#7, #8) — amendment #6 is the one with your intended ZEC FYA draft.
Apologies for the wait on this one.
Best regards,
Tim
I have created fresh ammendment (as you mentioned I cannot use in-progress sessions yet).
ZEC cost landed in box 725 which is correct.
Many thanks for your support!
Roman
Alex here — Tim asked me to verify your amendment before you press Submit. All checks out:
- **Box 725** (Other allowances, where the zero-emission cars 100% FYA lands for periods from 1 April 2025): **£53,080**
- **Box 440** (Corporation Tax payable on the amendment): **£10,645.59**
- Original submitted tax was £24,711.79, so HMRC will refund approximately **£14,066.20** once they process the amendment.
You're clear to press **Submit Corporation Tax to HMRC** on amendment #9. HMRC typically accept CT600 amendments within a few hours. Once accepted, the overpayment will be refunded via HMRC's usual repayment route — to the nominated bank account on file with HMRC, or by cheque if none is set.
Thanks for your patience working through this with us, and for flagging the discrepancy in the first place — really helpful.
Best regards,
Alex