R&D Tax Credits and TinyTax — What's Supported and What to Do

id: rd-tax-credits-and-tinytax title: R&D Tax Credits and TinyTax — What's Supported and What to Do category: ct600-filing tags: [R&D tax credits, research and development, RDEC, SME R&D relief, enhanced expenditure, blank accounts, CT600 amendment, boxes 530-535] applies_to: [trading] difficulty: intermediate last_updated: 2026-03-19 related: [understanding-your-tax-calculation, corp-tax-return]

@AdamsWinter files standard CT600 corporation tax returns. This guide explains what that means for companies with R&D tax credit claims, and what to do if your R&D claim was rejected because the accounts appeared blank or incomplete.

Does @AdamsWinter Support R&D Tax Credits?

No — @AdamsWinter does not currently support R&D tax credit claims. The CT600 we file is a standard corporation tax return. It does not include:

Enhanced R&D expenditure (Boxes 530–535)
SME R&D relief
Research and Development Expenditure Credit (RDEC)
R&D supplementary pages

If your company made an R&D claim, it would need to be included in an amended CT600 filed through specialist software or an accountant — not through @AdamsWinter.

Why HMRC May Say the Accounts Are "Blank"

@AdamsWinter files a standard loss or profit return. If your company is loss-making, the CT600 we transmit will correctly report:

Turnover (if any)
Costs and expenses
Trading loss (Box 780)

This is not blank — it is a valid CT600 for a loss-making company. However, HMRC's R&D processing team may describe it as "blank" in the context of an R&D claim because the return does not contain any enhanced expenditure figures or R&D supplementary data. Those fields are simply absent, not filled with zeros.

What to Do If Your R&D Claim Was Rejected

To claim R&D tax credits, you need to file an amended CT600 that includes the R&D supplementary pages. Your options are:

Use a specialist R&D tax adviser or accountant — they can prepare and file the amended return, including the enhanced expenditure calculations
Use HMRC's online CT600 service — this includes the R&D supplementary fields (Boxes 530–535)
Use commercial CT600 software that supports R&D claims

The amended return replaces the one @AdamsWinter filed. Since the original return was accepted, you have two years from the end of the accounting period to file the amendment (e.g., if your period ended 30 November 2025, the deadline is 30 November 2027).

Finding Your HMRC Correlation ID

If you need to provide an HMRC correlation ID (also called a transaction ID or document reference) to an adviser or HMRC, this is shown on the acceptance confirmation in your @AdamsWinter dashboard.

Log in → go to your company → your filed submission will show the HMRC transaction reference alongside the accepted status.

Common Questions

"Was the CT600 @AdamsWinter filed actually transmitted correctly?"

Yes. When @AdamsWinter shows a status of Accepted by HMRC, the return was transmitted and accepted. You can verify this via your HMRC online account (allow 3–5 working days for it to appear in CATO — Corporation Tax Online).

"Can I cancel the @AdamsWinter filing and refile with R&D included?"

You cannot cancel an accepted CT600 — it is already on HMRC's records. Instead, you file an amendment using specialist software or an accountant. The amendment adds the R&D data on top of the existing accepted return.

"Will @AdamsWinter support R&D claims in future?"

R&D claims are a specialist area with significant complexity. We don't have plans to support them in the current product. For now, companies with R&D claims should file their standard CT600 through @AdamsWinter and then work with an R&D specialist to file the supplementary amendment.

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