CT600 box 595 explained: Corporation Tax already paid
Short version. CT600 box 595 records Corporation Tax already paid for the return’s accounting period, excluding amounts HMRC has repaid. It is the payment figure, not the tax bill or the balance still to pay. Filing software uses it when calculating tax outstanding or overpaid.
If you have already paid and are ready to submit, follow the guide to filing a CT600 after paying Corporation Tax. If you have paid only part, see the partial-payment examples.
1. What box 595 means
Your return first works out the company’s tax liability. The reconciliation then takes account of payments and any relevant credits. Paying £2,000 towards a £3,800 bill does not change the company’s taxable profit or turn its tax liability into £1,800.
Box 595 is not a place for a planned payment, a tax estimate entered as though it had been paid, or the entire tax creditor balance from your accounts. Start with payments actually made for the period.
2. Work out the amount
Match the company’s payment records to its HMRC Corporation Tax statement. Total the relevant payments and subtract amounts already refunded. Do not include restitution tax or coronavirus support scheme overpayments. These exclusions come from HMRC’s box 595 instructions.
For example, payments of £1,250 and £750.25 total £2,000.25. If HMRC has already repaid £300 of those payments, the remaining amount for box 595 is £1,700.25. Keep a reconciliation showing how you reached it. HMRC’s guide asks for a detailed calculation in the computations.
A payment for VAT, PAYE or another Corporation Tax period is not a payment for this return. If you cannot tell where a payment belongs, resolve the allocation with HMRC before relying on it in your figures.
3. How boxes 595, 600 and 605 differ
- 595: the relevant tax already paid and not repaid.
- 600: tax still outstanding after the return’s reconciliation.
- 605: tax overpaid, including any relevant surplus or payable credits.
For an ordinary return with £3,800 liability and no other credits, £2,000.25 in box 595 leaves £1,799.75 outstanding. A £3,800 payment leaves no tax outstanding. A £4,000 payment produces £200 overpaid. The full HMRC reconciliation also includes other credit boxes, so this simple subtraction is not a formula for every type of CT600.
Box 600 is not a live HMRC account statement. Later payments, interest, penalties or an allocation problem can make the amount currently payable different from the filed return.
4. Check the payment period
HMRC’s payment-reference guidance explains that the 17-character reference changes with each accounting period. Check the reference used, the dates on your return and any refunds. A saved bank payee can still carry last year’s reference.
One set of annual accounts can cover two Corporation Tax returns. Identify the payment belonging to each return. Do not automatically divide a payment by the number of days or enter the full amount on both returns.
5. Enter the figure and review the return
Look for “Corporation Tax already paid” or box 595 in your software. Enter the reconciled amount, retaining pence where supported. Check the calculated balance and the final return before submitting.
For eligible active micro-entities, SimpleCompanyTax provides a separate payment field for each return and calculates the resulting outstanding amount or overpayment. You confirm the figures you supplied. Our filing walkthrough shows where to find the fields.
6. Official guidance
This is general guidance, not advice on your company’s tax position. If a payment or refund cannot be reconciled, check with HMRC or your tax adviser.