Corporation tax instalment payments UK: guide for large firms

Corporation tax instalment payments UK can change how large companies manage cashflow and budgeting across the year. This guide explains how instalments work, who might be affected and practical steps directors should take to stay compliant and avoid penalties.

What are corporation tax instalment payments?

Corporation tax instalment payments are a system where a company pays its corporation tax liability in periodic amounts during the accounting period, rather than in a single lump sum after the period ends. For larger companies the instalment regime is designed to spread tax payments across the year so HMRC receives amounts more closely aligned to when profits arise.

Key aims of instalment payments:

• Improve tax collection timing for HMRC by smoothing receipts across the tax year
• Reduce the burden for companies by splitting a potentially large tax bill into smaller payments
• Encourage companies to keep tighter short-term tax forecasts and cashflow planning

The mechanics and triggers for instalments differ from smaller companies that pay their corporation tax after the accounting period ends. If your business is approaching the threshold at which instalments may apply, it is important to understand the rules and prepare forecasts early.

Who is required to pay in instalments?

There is a statutory threshold and specific rules that determine whether a company is a "large company" for instalment purposes. The threshold and how it is applied depends on:

• Taxable profits for the accounting period
• The presence of associated companies, which can reduce the threshold available to each entity
• The length of the accounting period

Practical point: HMRC provides detailed guidance on which companies must pay by instalments and how to calculate the relevant thresholds. See HMRC guidance for the precise tests and examples: https://www.gov.uk/guidance/corporation-tax-paying-corporation-tax-by-instalments

Because associated companies and short or long accounting periods affect the calculation, directors should check the HMRC guidance or consult their accountant before assuming whether instalments apply.

How instalment schedules work

For companies that must pay by instalments, the general features are:

• Payments are usually made quarterly while the accounting period is in progress
• The number of instalments depends on the length of the accounting period and HMRC rules
• Each instalment is a portion of the estimated total corporation tax due for the accounting period
• If actual profits differ from estimates then a balancing payment or repayment follows after the period ends

Typical quarterly CT payments process

Although precise rules and due dates are set by HMRC and depend on your accounting dates, the common pattern for a 12 month accounting period is that instalments are paid in four roughly quarterly instalments. Companies calculate an expected tax liability and split it across those instalments.

Example scenario:

• Estimated corporation tax for the year: £120,000
• Quarterly instalments: 4 payments of £30,000
• After the year end the company files its return and either makes a balancing payment or claims a repayment if instalments exceeded the final liability

Note: The above is a simplified illustration. HMRC requires specific calculations for short accounting periods and for companies with associated entities. Always refer to the HMRC guide for calculation rules.

Calculating instalments and submitting payments

There are two linked tasks: calculating how much to pay, and ensuring the payment reaches HMRC by the due date.

Calculating instalments

• Start from your best estimate of taxable profits for the accounting period. Use recent management accounts and forecasts to inform this estimate.
• Apply corporation tax rates relevant to the accounting period to estimate the tax due.
• Divide the estimated tax across the required number of instalments according to HMRC rules. For many large companies this will mean quarterly CT payments.
• If your estimate changes materially, you should revise instalment amounts and be prepared for a balancing payment at the end of the period.

Submitting payments

Companies can pay corporation tax by several routes depending on timing and preference. Common payment methods include:

• Online or telephone banking (Faster Payments) using the correct HMRC bank details
• CHAPS for same-day large value payments
• Direct debit via HMRC for some company payments
• BACS for scheduled transfers

Always use the correct payment reference as set out by HMRC so the payment is allocated to the right company and accounting period. Late or misapplied payments can trigger interest and penalties.

For guidance on methods and bank details see HMRC: Paying corporation tax.

Interaction with CT61 and common confusions

You may see the term CT61 in some contexts. CT61 is a separate HMRC form historically used by some payers to report tax deducted from interest and dividends. It is not the same as making corporation tax instalment payments.

To avoid confusion:

• CT61 is not the mechanism for paying corporation tax instalments
• CT61 reporting relates to specific tax withheld scenarios and is not generally used by companies for quarterly instalments
• Use the HMRC instalments guidance for corporation tax payments and the CT61 form guidance for reporting interest withholding if relevant to your business

If you are unsure whether CT61 applies to any part of your business activity, consult your accountant.

Deadlines, interest and penalties

Late or incorrect instalment payments attract interest and potentially penalties. Key points:

• Interest is charged on late payments from the due date until the payment is made
• Penalties can apply for late filing of the corporation tax return and for late payment of the balancing amount
• Underpayments during the year can increase cash cost later when balancing payments and interest are taken into account

Practical ways to avoid charges:

• Keep conservative estimates to avoid underpaying instalments
• Set up payment processes and internal calendars so instalments are paid on time
• Use management accounts and forecasts to adjust instalments if profits are tracking differently to plan

For exact interest rates and penalty schedules, consult HMRC.

Special situations: short accounting periods and associated companies

Two common complications for large company tax are short accounting periods and groups of associated companies.

Short accounting periods

• If your accounting period is shorter than 12 months the number of instalments and their timing can change
• The instalment rules treat short periods differently and HMRC provides worked examples

Associated companies

• Where two or more companies are associated, the instalment threshold and the instalment obligations can be apportioned across the group
• Associated companies may find their instalment obligations kick in at lower individual profit levels because the threshold is divided

Because both factors materially change calculations, directors should involve their accountant early if either applies.

Cashflow and planning implications for large company tax

Paying corporation tax in quarterly instalments affects working capital. Practical steps to manage impact:

• Build instalment dates into your cashflow forecasts and bank liquidity planning
• Use rolling forecasts and update them at least monthly to capture profit trends that affect tax liability
• Consider timing of capital allowances and discretionary expenditure to manage taxable profits within the accounting period
• Maintain a tax reserve cash pot to smooth payments and reduce risk of last-minute borrowing

Figures can help with budgeting, forecasting and scenario planning. See our services on Cash Flow Management and Budgeting & Forecasting for practical support.

Reporting and management information

Good management reporting makes instalment obligations easier to manage. Items to include in monthly or quarterly packs:

• Year-to-date taxable profit estimate
• Estimated corporation tax liability and instalment schedule
• Reconciliation of taxable profit to statutory profit, highlighting timing differences and one-off items
• Cash required for upcoming instalments compared to cash available

For support building reports that directors and boards can rely on, see our Management Reporting and Statutory Accounts & Tax services.

When to seek professional advice

You should speak to an accountant if any of the following apply:

• You expect taxable profits to be near any HMRC instalment threshold
• You have associated companies or group structures
• Your accounting period is unusually short or long
• You need help forecasting and modelling instalment cashflows

A specialist adviser can model likely instalments, handle payments, and help reduce the risk of penalties and interest.

Practical checklist for company directors

• Confirm whether your company meets HMRC rules for instalment payments using current guidance
• Build instalment amounts and dates into your cashflow forecast
• Set up payment routes well before due dates and confirm reference details with HMRC
• Reforecast taxable profits regularly and adjust instalments if necessary
• Keep records of calculations and communications in case HMRC queries arise

Useful HMRC links and further reading

• HMRC guidance on paying corporation tax by instalments: https://www.gov.uk/guidance/corporation-tax-paying-corporation-tax-by-instalments
• General corporation tax payment methods and matters: https://www.gov.uk/pay-corporation-tax

UK tax and legal accuracy

This article is for informational purposes only and does not constitute professional tax or financial advice. Please speak to a qualified accountant before taking action. Relevant tax year: 2026/27.

Frequently asked questions

What level of profit makes a company a "large company" for instalments?

HMRC sets the threshold and applies adjustments for associated companies and accounting period length. Check HMRC guidance or speak to your accountant to determine whether your company exceeds the instalment threshold in a particular accounting period.

How often are quarterly CT payments due?

Where instalments apply, payments are usually made quarterly during the accounting period. The exact number and timing depend on accounting period length and HMRC rules. Use forecasts to plan for each instalment.

Is CT61 the same as corporation tax instalments?

No. CT61 is a different HMRC reporting form historically used for certain interest and dividend withholding reporting. It is not the mechanism for paying corporation tax instalments.

What happens if I underpay instalments?

Underpaying instalments can lead to a larger balancing payment at year end plus interest on late payments. In some cases penalties may apply. Regular reforecasting and conservative provisioning will reduce the risk of underpayment.

Can I change instalment amounts if my profit forecast changes?

Yes. If your estimate of taxable profits changes materially, you should revise instalment calculations and be prepared for the balancing mechanics at year end. Speak to your accountant for guidance on safe approaches to revising instalments.

Summary and next steps

For large companies, corporation tax instalment payments UK introduce regular cashflow obligations that need active forecasting and careful payment practices. Start by checking HMRC guidance and assessing whether your company meets the instalment tests. Then build instalment dates into your cashflow forecasts, set up reliable payment routes and keep records of calculations.

If you would like help modelling instalments, building forecasts or managing payment schedules, Figures can help. Book a discovery call with our team to discuss your situation and get practical support: book a discovery call.