Ask most directors what their corporation tax bill will be and the honest answer is that they will find out when the accountant tells them. That is usually weeks before the payment date, sometimes days. The number itself may be perfectly correct. The problem is that it arrives at the one point in the cycle where no action can change it.

We see this across established limited companies that are well run in every other respect. Pricing is thought through, hiring is planned, invoices go out on time. The tax position is the one number in the business that nobody looks at until it is final.

Corporation tax is not an event at the end of the year. It accrues quietly with every profitable month, while the cash that will eventually settle it is being drawn as dividends, spent on equipment or used to cover a slow payer.

Nobody does this recklessly. Directors draw what the bank balance appears to allow, because the bank balance is the only live number in front of them. The liability sitting behind it is invisible until someone calculates it. By the time the figure is produced, the company has already made twelve months of decisions on incomplete information, and the money that would have covered the bill has gone out of the door.

Since April 2023 there has been no one flat rate on non ring fence profits. For corporation tax years starting 1 April 2026, HMRC’s rates and allowances set the small profits rate at 19 per cent for profits under £50,000 and the main rate at 25 per cent for profits over £250,000. Between those two limits the main rate applies and is reduced by marginal relief, using a standard fraction of 3/200, so the effective rate climbs gradually rather than jumping.

That middle band is where most of the companies we work with sit. It means your effective rate moves with your profit, and a decision taken in month nine can change what you pay.

The standard model is retrospective. Records are collected some months after the year end, accounts are prepared, the CT600 is drafted, and the director is told the result. Everything is filed correctly and on time, and the client learns the figure at the very end of the process.

It is compliance done properly and advice not done at all. The accountant is reporting history, which is a legitimate job, but it is the wrong job if the owner wanted to influence the outcome. By then the salary has been set, the dividends have been taken, the VAT scheme has run for another year and the equipment either was or was not bought before the year end.

There is a difference between being told what you owe and being shown what you are heading towards. The first is a demand with a date on it. The second is information you can act on.

The marginal relief band is where that difference bites hardest. A company sitting between the £50,000 and £250,000 limits for 2026/27 has an effective rate that moves with profit, which means pension contributions, timing of capital spend and the salary and dividend mix all have a measurable effect. Make those calls before the year end and they count. Discover the position afterwards and you are simply reading the result of choices you made without the relevant number in front of you.

The companies we work with are established limited companies turning over £150,000 or more: consultants and contractors with high invoice values, and construction and trades businesses carrying staff and overheads. On profits, most of them sit above the £50,000 lower limit, which puts them inside the marginal relief band for 2026/27.

In almost every case the pay structure was set once, often in April, and then left alone. Salary at a figure someone suggested years ago, dividends drawn when the account looks healthy, no review of whether the split still suits the profit the company is now making. The structure was reasonable when it was chosen. It simply stopped matching the business.

What then happens is quiet. Profit rises through the year, the company crosses further into the marginal relief band, and the effective rate rises with it. Nothing in the business feels different. The work is the same, the team is the same, the invoices look the same as last quarter.

The owner finds out about it a year or more later. A good year on the profit and loss account turns into a tax bill that is noticeably larger than the previous one, and the explanation arrives at the same moment as the demand. Had anyone mentioned it in month eight, there would have been options. By the time the accounts are signed, there are none.

The filing calendar makes this easy to miss. Under GOV.UK guidance, a Company Tax Return is due twelve months after the end of the accounting period it covers, while the tax itself falls due earlier. Firms that work to the filing deadline rather than the payment deadline can legitimately leave the figure uncalculated for most of a year.

So the question of what the company owes often goes unanswered until someone sits down to prepare the return. If nothing in the routine forces an earlier look, nothing produces an earlier answer. That is a process choice rather than a rule of tax, and it is the part that can be changed.

For taxable profits up to £1.5 million, HMRC requires corporation tax to be paid nine months and one day after the end of the accounting period. Companies above that level pay in instalments, which is a different timetable again. For most established limited companies, the single payment date is the one that matters.

Nine months is long enough for the money to have been spent. Dividends have been drawn, a van or a server has been bought, a hire has been made. The cash that would comfortably have covered the bill left the company months ago, and the director is now funding a historic liability out of current trading. That is the real cost of finding out late.

The fix is unglamorous. Bookkeeping is kept current so the profit figure is never more than a few weeks old. The set-up gets reviewed before the year end rather than after it, covering structure, VAT scheme, salary and dividends. The corporation tax position is forecast, and the number reaches the director about a month before the payment date, with the dividend headroom alongside it.

None of that requires special software or a clever scheme. It requires the work to be done in a different order. Once the books are current, forecasting the liability is routine, and the forecast is what turns a demand into a decision.

When the number arrives early, two things follow. The money gets set aside instead of drawn, so the payment date is an administrative event rather than a cash problem. And the choices move forward into the period where they still count.

Salary and dividend mix, pension contributions, the timing of capital spend, and whether the VAT scheme still fits the cost profile all get looked at while the year is open. We saw this with a procurement consultant whose box 4 was nearly empty because his costs were overseas software and reverse charge services. Moving him to the flat rate scheme brought his VAT bill down every quarter with no change to turnover, and he now gets his corporation tax and dividend position a month ahead.

The test is straightforward. If the size of your corporation tax bill surprises you in the final month, the information reached you too late to be useful, whatever the number turned out to be. A well run company should be able to say roughly what it owes long before the payment date, because the figure has been tracked rather than discovered.

If you are not sure where you stand, the practical first step is to check your own dates. Find your accounting period end, add nine months and one day, and see how close that date is. Then ask whether anyone has given you a figure to go with it.