CT600A and the s455 Charge: Filing Loans to Participators with WeFile

If your limited company has lent money to a director or a shareholder — or to anyone connected with them — and any part of that loan was still outstanding at the end of the accounting period, HMRC wants to know about it. The mechanism is supplementary page CT600A, and the tax it triggers is the section 455 charge.

s455 catches out more owner-managed companies than almost any other part of the corporation tax return. It is not a penalty and it is not permanent — it behaves more like a deposit that becomes repayable once the loan is cleared — but it is charged at 33.75% of the outstanding balance (rising to 35.75% for loans advanced on or after 6 April 2026), and it falls due at exactly the same time as your corporation tax.

CT600A is now supported in WeFile from end to end: a dedicated step in the filing wizard, automatic s455 calculation at the correct historic rate for each loan, automatic relief routing between Part 2 and Part 3, boxes A1 to A80 transmitted inside the same CT600 submission, a printable CT600A form, full support for long periods that split into two returns, and complete Developer API coverage.

This article covers both sides: the tax itself, and exactly how WeFile handles it.

CT600A — Loans to participators by close companies — is one of the supplementary pages that attach to the main CT600 return. You need it when all three of the following are true:

• Your company is a close company. Broadly, that means it is controlled by five or fewer participators, or by its directors — which describes the overwhelming majority of UK owner-managed limited companies.
• The company made a loan or advance to a participator, or to an associate of a participator, at some point up to the end of the accounting period.
• Some part of that loan was still outstanding at the end of the period, or was repaid, released or written off in a way that creates a relief claim.

The classic case is an overdrawn director's loan account at the year end. If money has been drawn out of the company that was not salary, not a properly declared dividend and not a reimbursed business expense, that balance is a loan to a participator.

Close companies and participators in plain English

A participator is anyone with a share or interest in the capital or income of the company. In a typical small company that means the shareholders, and usually the directors too. It is a deliberately wide definition — it can extend to people holding loan capital or certain rights over the company's income.

An associate of a participator is broadly a spouse or civil partner, a parent, grandparent, child, grandchild, brother or sister, a business partner, or certain trustees. This is the part people miss most often: a loan to a shareholder's spouse is inside the rules even though the spouse holds no shares.

Two points worth being clear about:

• There is no de minimis for s455. A £500 overdrawn balance is chargeable in exactly the same way as a £500,000 one. The £10,000 threshold people sometimes quote relates to the separate beneficial loan interest benefit-in-kind under the employment income rules, not to s455.
• s455 and the benefit-in-kind can both apply to the same loan. They are different taxes, reported on different forms, and one does not replace the other.

The mechanics are straightforward once you separate the charge from the relief:

1. The charge. s455 is charged on the loan balance outstanding to a participator at the end of the accounting period, at the rate in force when that loan was advanced.
2. The due date. It is payable nine months and one day after the end of the accounting period — the same deadline as your corporation tax. It appears alongside corporation tax in the total tax payable on your CT600.
3. The relief. Once the loan is repaid, released or written off, the s455 becomes repayable to the company. Crucially, it is not refunded automatically. Relief has to be claimed, and it is only due nine months and one day after the end of the accounting period in which the repayment happened.

The s455 rate schedule

The s455 rate tracks the dividend upper rate, so it has changed several times. WeFile applies the full historic schedule:

Two details that materially affect the figures, and which many packages get wrong:

• Each loan is charged at its own rate. Following HMRC's guidance at CTM61505, WeFile charges each loan row at the rate in force on the date that particular loan was advanced — not one blanket rate for the whole period. If your accounting period straddles 6 April 2026, some loans are charged at 33.75% and others at 35.75%, and the wizard displays "mixed rates" rather than quoting a single misleading percentage.
• Relief is given at the rate originally charged. A loan advanced in 2020 and repaid today releases relief at 32.5%, not at today's rate. WeFile matches each relief entry back to the rate that was charged on the underlying loan, prefilling the original loan date for you where it can identify the matching advance.

On the paper form, relief is split across two parts, and deciding which part a repayment belongs in is one of the most common sources of error. In WeFile you never have to make that decision.

You record every repayment, release or write-off in a single list, with the participator's name, the amount repaid and/or the amount released or written off, and the date. WeFile then works out where each entry belongs by comparing that date with the nine-month deadline after your period end:

• Part 2 (boxes A40 to A45) — relief that is already due for this return. The tax is reduced now.
• Part 3 (boxes A60 to A70) — relief for loans repaid later, claimed now because it has become due.

Because the routing is derived rather than stored, the same entry can correctly sit in Part 2 for one return period and Part 3 for another — which matters for long periods that split into two returns. Month-end dates are handled properly too: a repayment dated 30 September against a 31 December year end lands in Part 2, where a naive nine-month calculation would wrongly push it into Part 3.

This is the single most valuable piece of logic in the feature, so it is worth explaining carefully.

If a loan is repaid more than nine months after the end of the period, the relief is not due when you file this return. It becomes due nine months and one day after the end of the accounting period in which the repayment actually happened — which can be well over a year later.

WeFile handles this correctly by deferring such entries. The s455 is charged and paid now, the relief is held back, and it is reclaimed later either through an amended return or through HMRC's form L2P. Deferred entries are shown separately in the wizard so you can see exactly what is being held over and why.

To see why this matters, take a £40,000 loan repaid after the deadline. Treat the relief as immediately due and the return shows £8,437.50 of s455 payable. Treat it correctly as deferred and it shows £13,500 — a £5,062.50 difference on a single row, and the wrong answer means either an underpayment to HMRC or a relief claimed a year too early.

Here is how it looks in practice.

On step 1 of the filing wizard you confirm whether the company is a close company. Answer yes and a new Loans step appears in the wizard sidebar. Answer no and nothing changes — CT600A is not added to your return and nothing extra is transmitted.

On the Loans step you enter:

• Brought-forward balance — any participator loan already outstanding at the start of the period.
• Box A5 — whether the loans were made before the end of the period. This is a genuine HMRC question and is transmitted on the form.
• Loans made in the period — participator name, amount and date advanced, one row per advance.
• Repayments, releases and write-offs — name, the amount repaid and/or released or written off, and the date. You can optionally record the date of the original loan so relief is rated correctly.

As you type, a live summary panel derives every total on the form: A15 and A20 (loans and tax chargeable), A40 and A45 (Part 2 relief), A65 and A70 (Part 3 relief), A75 (total loans outstanding) and A80 (s455 payable). Nothing is stored as a total — every figure is recalculated from your rows, so it can never drift out of step with the detail.

All dates are shown and entered in dd/mm/yyyy throughout the wizard and the filing detail view. You can record up to 20 loan rows and 20 relief rows per return.

Validation that stops HMRC rejections

HMRC applies business rules to CT600A after the schema check, which means a technically valid return can still be rejected. WeFile validates the things that actually cause those rejections, before you submit:

• Future-dated relief is blocked. HMRC business rule 9431 rejects any repayment, release or write-off dated later than today. WeFile catches this at the Loans step rather than letting it fail at the gateway.
• Loan dates must fall inside the period of account. A loan dated outside the period is flagged, because it cannot belong in Part 1 of this return.
• Nothing is silently dropped. If any row cannot be processed, submission is blocked with a clear message instead of transmitting understated figures. This applies to both the wizard and the Developer API.
• Empty blocks are omitted, not zero-filled. Several CT600A totals are typed by HMRC as non-zero, so WeFile omits the entire block when a total is nil rather than sending a zero — the difference between acceptance and a schema error.

Validation errors are surfaced at the Loans step and again on the Review step, where Continue is disabled until they are resolved. You should never discover a CT600A problem at the point of submission.

CT600A is not a separate filing. It is transmitted inside the same CT600 submission, and WeFile wires the figures into the main form for you:

• Box 95 is ticked automatically to declare that supplementary page CT600A is attached. You are never asked about it.
• Box 480 — s455 tax payable, taken from box A80.
• Box 485 — ticked only where Part 3 relief is being claimed.
• Boxes 510 and 525 — total tax chargeable and payable, including s455 on top of corporation tax.
• Box 475 stays corporation tax only, exactly as HMRC requires.

One submission, one IRmark, one confirmation. With CT600A included, WeFile now covers 81 CT600 boxes across 10 categories — you can see the full list on our changelog and coverage page.

An accounting period longer than 12 months has to be filed as two corporation tax returns, and CT600A has to be apportioned between them. WeFile does this automatically:

• Loans are allocated by the date advanced, so each advance is charged in exactly one of the two returns. There is no double counting: two loans of £40,000 and £20,000 produce a total charge equal to £60,000 at the applicable rate, split across the two returns.
• Relief entries are assigned to the sub-period you choose. Repayments usually fall after both sub-periods have ended, so they cannot be allocated by date without being lost — the wizard lets you assign each one explicitly.
• Brought-forward balances carry through from one sub-period to the next.
• Each return gets its own CT600A, and each can be downloaded as its own PDF.

s455 is a standalone charge bolted on after corporation tax. It is not part of the company's tax charge for accounting purposes, and it must not appear in the financial statements.

WeFile keeps this separation absolutely clean. Your profit and loss account, your balance sheet, and the iXBRL accounts filed at Companies House are entirely unaffected by s455 — chargeable profits, the corporation tax charge and profit for the year are all untouched. The s455 figure appears only where it belongs: on the CT600, on the CT600A, and as its own clearly labelled block in the corporation tax computation.

We verified this end to end against live submissions: the accounts document filed at Companies House contains the corporation tax figure and no trace of the s455 charge.

Every CT600A filing comes with a complete document set:

• CT600A PDF — a faithful reproduction of HMRC's official form, populated with your figures, alongside your CT600, accounts and tax computation.
• Continuation schedules — the paper form only has six row slots but the totals cover up to 20 rows, which is a classic way for a printed form to contradict its own totals. Where you have more rows than slots, WeFile appends a paginated continuation schedule and marks the truncated table, so the detail always ties to the totals.
• Per-return versions for split periods — for a long period, you can download the CT600A, CT600 and tax computation for each sub-period individually, each matching the return that was actually submitted for it.

Your figures stay pinned to what you actually filed

Because deferred relief becomes due as time passes, a naive system would quietly change the numbers on a return you filed months ago — the same filing showing £13,500 one day and £8,437.50 the next, with nobody touching anything.

WeFile pins the figures on a filed return to the date it was submitted. Re-open a completed filing or re-download its PDFs a year later and you see exactly what was filed, which is what you need when HMRC asks.

Separately, where relief that was deferred at the time of filing has since become due, the filing shows an advisory note telling you so — along with the amount you can now reclaim through an amended return or form L2P. You get both truths: the return as filed, and the money you are now owed.

In WeFile, dormant filings and CT600A are mutually exclusive, and this is deliberate.

Any movement on a participator loan — an advance or a repayment — is a significant accounting transaction under section 1169 of the Companies Act 2006, which breaks dormancy. And an outstanding loan is a debtor, which the dormant accounts format filed at Companies House simply cannot represent, since it only carries called-up share capital, cash and reserves.

So if you mark a filing as dormant, no CT600A is transmitted. Any loan schedule you have already entered is preserved rather than deleted, so toggling dormant off restores your data exactly as it was.

CT600A figures feed forward: a change to loans in one sub-period changes the brought-forward balance of the next. Allowing edits after submission would mean HMRC holding two returns that contradict each other.

Once an HMRC submission has been accepted, WeFile therefore blocks changes to the close-company answer and the CT600A data, and points you to the amendment flow instead. The lock is narrow by design — it only rejects genuine changes, so re-saving identical data still works normally, and it never blocks submitting the remaining sub-period of a split filing.

Need to correct a filed CT600A? Create an amendment. Your loan schedule, relief rows and sub-period assignments are all carried across to the new draft.

CT600A is available through the WeFile Developer API, not just the wizard. Set isCloseCompany and include a supplementaryPagesData.ct600a object when saving a filing:

{
  "isCloseCompany": true,
  "supplementaryPagesData": {
    "ct600a": {
      "applies": true,
      "beforeEndPeriod": true,
      "broughtForward": 10000,
      "loans": [
        { "name": "J Smith", "amount": 40000, "dateAdvanced": "2025-09-15" }
      ],
      "reliefs": [
        { "name": "J Smith", "amountRepaid": 15000, "date": "2026-06-01" }
      ]
    }
  }
}

Points to note:

• applies and beforeEndPeriod are always required.
• Partial saves are merged key by key. Omit loans and your stored schedule is preserved; send an explicit empty array to clear it. This means you can flip a single flag without destroying the schedule.
• Row date rules run at submit time, not on save, so a saved row can still be rejected at submission if its dates are invalid.
• Request the ct600a_pdf document type to download the completed form, with an optional subPeriod for split filings.
• GET /v1/filings returns isCloseCompany and supplementaryPagesData, so CT600A is readable as well as writable.

Full reference, schemas and worked examples are in the API documentation.

• Not answering the close-company question. If you skip it, the Loans step never appears and the loan is never declared. If your company is controlled by five or fewer participators, or by its directors, say yes.
• Treating drawings as dividends after the fact. A dividend has to be properly declared and supported by distributable reserves. Money simply taken out is a loan.
• Assuming a repayment after the year end removes the charge. It gives relief — but the timing of that relief is what determines whether it reduces this return or has to be reclaimed later.
• Forgetting loans to family members. Associates of participators are inside the rules even if they hold no shares.
• Thinking s455 is lost money. It is recoverable once the loan is cleared, but only if you actually claim it. Do not leave it with HMRC.
• Netting off separate loans and repayments. Record each advance and each repayment as its own row so the rates and the relief timing are applied correctly.

Is there a minimum balance before s455 applies?

No. There is no de minimis threshold for s455 — any outstanding participator loan is chargeable. The £10,000 figure people often mention relates to the separate benefit-in-kind on cheap or interest-free loans.

Can I be charged s455 and a benefit in kind on the same loan?

Yes. They are separate charges under separate legislation and both can apply.

How do I get s455 back once the loan is repaid?

Either by amending the return for the period in which the charge arose, if you are still in time, or by claiming with HMRC's form L2P after that. WeFile tells you when deferred relief has become due, and how much.

Does WeFile charge extra for CT600A?

No. Supplementary page CT600A is included in your filing at no additional cost, and it is submitted inside the same CT600 return.

Does the s455 charge appear in my accounts at Companies House?

No. It is deliberately kept out of the profit and loss account and the iXBRL accounts. Only the corporation tax charge appears there.

Which other CT600 supplementary pages does WeFile support?

CT600A is fully supported today. Pages CT600B to CT600P are not currently supported.

What if my accounting period is longer than 12 months?

WeFile splits it into two returns automatically and apportions the loans and relief between them, with a separate CT600A for each.

If you have an overdrawn director's loan account, CT600A is not optional — and getting the relief timing right is worth real money. WeFile now handles the whole thing: the correct rate for every loan, the right part of the form for every repayment, the deferral treatment HMRC actually requires, the boxes on the main return, and a printable form for your records.

Log in to your account to start a return, or take a look at the Developer API if you file at volume. Questions about your own position? Get in touch — we are happy to help.