R&D Tax Credits and TinyTax — What We File and What We Don't

TinyTax files CT600 corporation tax returns and micro-entity statutory accounts to HMRC and Companies House. This guide explains what's included in a TinyTax submission and why R&D tax credit claims are outside our scope.

What TinyTax Submits to HMRC

Every TinyTax submission includes:

• CT600 return — the main corporation tax form with your trading figures, tax calculation, and any loss carry-forwards
• iXBRL statutory accounts — your profit & loss account and balance sheet in HMRC's required format
• Tax computations — showing how your taxable profit and tax liability were calculated

The iXBRL accounts generated by TinyTax are correctly tagged to the HMRC schema. Financial figures including turnover, costs, gross profit, and net profit/loss are all included and tagged.

R&D Tax Credits Are Not Supported

TinyTax does not currently support Research & Development (R&D) tax credit claims. This means the CT600 we file does not include:

• R&D enhanced expenditure (Boxes 530–535 on the CT600)
• SME R&D relief calculations
• Research and Development Expenditure Credit (RDEC)
• The CT600L supplementary pages

If HMRC's R&D team queries your submission and says the accounts contain "no financial figures" or "no R&D data", this is because the R&D boxes are absent from the return — not because the statutory accounts are malformed or blank. The underlying accounts and CT600 figures are correct.

How to Claim R&D Tax Credits

To claim R&D tax credits, you'll need to file an amended CT600 that includes the R&D supplementary pages. Since the original return was already accepted by HMRC, the amendment adds the R&D data on top — you do not need to cancel or refile the original return.

The most practical routes are:

1. R&D tax specialist or accountant — they can prepare and file the amendment, including the CT600L pages and enhanced expenditure calculations
2. HMRC's own CT600 online service — includes the R&D supplementary pages
3. Commercial CT600 software that supports R&D claims (e.g. Taxfiler, Andica)

Amendment Deadline

You generally have two years from the end of the accounting period to file an amended return. For example, for a period ending 30 November 2025, the amendment deadline is 30 November 2027.

Confirming Your Submission Details

If HMRC or an R&D adviser asks for evidence that your original CT600 was filed correctly, you can provide:

• The transaction ID from your TinyTax dashboard (shown on the submission confirmation page)
• The acceptance timestamp — HMRC accepts returns within seconds via the Government Gateway
• The iXBRL accounts file — downloadable from your TinyTax dashboard

Common Questions

"HMRC said the accounts contain no financial figures — are they correct?"

Yes. The accounts TinyTax filed contain all the financial figures from your P&L and balance sheet, correctly tagged in iXBRL format. When HMRC's R&D team describes the accounts as having "no figures", they mean the R&D-specific boxes (530–535) are empty — which they are, because TinyTax does not file R&D supplementary pages.

"Do I need to refile my original return before claiming R&D?"

No. Your accepted CT600 remains valid. You file an amendment alongside it — the amendment adds the R&D data without replacing the original.

"Will claiming R&D change my corporation tax liability?"

Yes — R&D relief typically reduces your corporation tax liability or generates a payable credit. Your R&D adviser will calculate the adjusted figures as part of the amendment.