The Hidden Tax Change Putting Pressure on UK Business Cash Flow

It’s easy to assume a business in a cash crunch is underperforming. But plenty of profitable, well-run companies with steady demand, healthy margins and consistent trading patterns still find themselves with cash flow problems at certain points in the year. The cause is rarely performance and usually timing. Cash has to leave the business before the revenue intended to cover it has arrived.

Tax is one of the sharpest versions of that problem, and unfortunately one of the least discussed. Since April 2023, a growing number of owner-managed businesses have been quietly pulled into an accelerated HMRC Corporation Tax schedule, paying through the year rather than in a single sum after their financial year ends. Not a lot of SMEs expect it. The shift catches them out because the tax now starts leaving the business while the accounting year is still running, often before the revenue meant to cover it has arrived. For an otherwise healthy business, the cash flow impact can be significant. In this guide, we’ll explain who’s affected, how the regime works, and what businesses can do to stay ahead of it.

What Are QIPs and Which Businesses Do They Apply To?

Quarterly Instalment Payments (QIPs) have been part of the UK Corporation Tax system since 1999. For most of that time, they were treated as a large-company obligation, not a concern for growing SMEs or owner-managed businesses.

That changed in April 2023, around the time HMRC widened the definition of “associated companies” used to work out whether a business crosses the QIP threshold. Until then, the threshold was only shared between companies that belonged to the same formal corporate group. In practice that meant companies tied together by majority share ownership: one company owning more than half of another, or a single parent company owning more than half of several. This arrangement is known as a ‘51% group’. Importantly, if one person owned two companies separately, with no parent company linking them, the two were not counted against each other.

From April 2023, that test was replaced by a wider one based on “associated companies”. Two companies are associated when they are controlled by the same person or people, whether or not a corporate group sits between them. So, an owner who holds two or three separate limited companies outright, each trading entirely on its own, now has them treated as associated, even though there is no holding company joining them up. 

The headline QIP threshold is taxable profits above £1.5 million in a twelve-month period, but that figure is now split equally across every company under that common control. Therefore, an owner running two separate limited companies sees the threshold halved to £750,000 per entity. A third company brings it down to £500,000 each. A fourth, and it falls to £375,000. What once felt like a threshold designed for major corporates has become a very real consideration for multi-entity owner-managed businesses.

Two further changes have sharpened the impact. The first was the Corporation Tax rate rising to 25% on profits above £250,000 from April 2023, meaning QIP bills are larger than they would have been under the previous 19% flat rate. The second is that HMRC has been actively writing to businesses it believes should already be operating under QIPs. For those who entered the regime unprepared, the financial exposure has grown considerably.

How the QIP Regime Works and Why Timing Creates the Problem

Under the standard Corporation Tax payment regime, a business settles its liability in a single payment, due nine months and one day after the accounting year ends. The tax is known, the date is fixed, and a well-run business can plan for it. Under QIPs, the tax is payable in four instalments. The first falls during the accounting period itself, long before the final profit figure is known, with the rest following at three-month intervals. Also, payments are based on an estimate of profits rather than confirmed figures, which can negatively impact how cash is managed in a business throughout the year.

HMRC does provide a grace period: a business crossing the profit threshold for the first time is not required to adopt QIPs until the following accounting period. That grace period offers short-term relief, but it creates a compounding problem a year later. The deferred lump-sum payment for the grace year falls due at almost exactly the same time as an in-year instalment for the next, meaning a business can find itself funding what feels like two years of Corporation Tax within the same few-week window.

For businesses that were not modelling this in advance, the experience is a cash flow shock, and it is happening to otherwise financially healthy businesses right now.  The cost of getting behind has also risen. Interest on underpaid instalments currently runs at 6.25% (the rate set from December 2025), and once a payment slips past the normal due date, the higher general late-payment rate of 7.75% applies. A penalty regime sits on top of that where instalments are deliberately missed or underpaid. Getting behind is not just stressful. It is expensive.

Key HMRC Deadlines Businesses Need to Be Aware of in Summer 2026

Several significant tax payment dates are arriving in close succession, knowing and understanding them is pivotal to planning around them.

• Corporation Tax for businesses with an August 2025 year-end was due by 1 June 2026, a deadline that has now passed. Those with a September 2025 year-end still have until 1 July 2026.
• On the VAT side, the 7 June 2026 deadline for businesses trading on a February to April 2026 quarter has gone. But those with a March to May 2026 quarter must still submit and pay by 7 July 2026.
• Directors and sole traders with income outside PAYE also face the 31 July self-assessment payment on account, adding further pressure to an already concentrated period of outgoings.
• For a growing, profitable business, this cluster of deadlines is entirely manageable with preparation. Without it, the pressure can arrive quickly and leave limited room to respond.

The Wider Tax Environment Making This Harder for SMEs

The QIP timing issue does not exist in isolation. A broader set of tax and compliance changes is increasing both the financial and administrative demands on UK businesses at the same time.

Making Tax Digital for Income Tax began its first phase on 6 April 2026, requiring sole traders and landlords with qualifying income above £50,000 to keep digital records and submit quarterly updates to HMRC. Corporation Tax late-filing penalties also rose for returns due on or after 1 April 2026, the first increase since 1998, with a one-day-late penalty doubling from £100 to £200 and repeat late filers facing considerably more. Dividend tax rose by two percentage points for basic and higher-rate taxpayers from April 2026, raising the cost of extracting profits for many owner-managers.

According to research by the Federation of Small Businesses, UK business owners already spend an average of £4,500 and 44 hours each year on tax compliance, with three in five reporting that dealing with HMRC has increased their personal stress. The direction of travel is clearly towards more obligations, tighter timelines, and less tolerance for late or incorrect payments. For SMEs trying to manage growth, invest in their teams, and maintain supplier relationships, having a portion of working capital tied up in advance tax payments is a genuine operational constraint, not a theoretical one.

How Revenue-Based Finance Helps Protect Working Capital Around These Periods

With those deadlines stacking up and Corporation Tax now leaving the business through the year rather than after it ends, taking a typical case puts the pressure in perspective.

A business with monthly card takings of £18,000 faces a Corporation Tax instalment of £35,000 due in six weeks. Current revenue reserves are committed to stock and payroll. Drawing that £35,000 from working capital might be possible, but it leaves the business exposed for the weeks that follow: with the buffer gone, a single late customer payment, an unexpected repair or one quiet trading week could be enough to leave wages, stock orders or supplier invoices unfunded. A revenue-based cash advance offers another route, covering the instalment upfront so those reserves stay where they are.

The cost of servicing this funding is structured differently from a traditional loan. Rather than a rate of interest that accrues over time, revenue-based finance carries a single fixed fee, agreed at the outset, and is repaid through a “split”. The split is an agreed percentage of card sales. Both the fee and the split are fixed for the individual business at the point the funding offer is accepted, before any money is released.

As an illustration, that fixed fee on a £35,000 advance might bring the total repayable to around £42,000, a factor of roughly 1.2 on the amount advanced. The fee and the split quoted to any given business depend on its trading profile, so both figures here are purely illustrative.

Repayment would come through a split of card takings, set in this example at 10%. On £18,000 of monthly takings, that works out at around £1,800 over a typical month. Because the split is taken from card sales as they are processed through the month, the amount collected rises and falls with daily takings, resulting in smaller payments when trade is quieter and larger when it is strong, spreading the cost across the trading period rather than concentrating it into a single damaging withdrawal.

For a business in that position, the benefit is worth stating plainly. The HMRC deadline is met on time, HMRC interest charges are avoided, and the cash set aside for stock, wages and suppliers stays exactly where it is. There is no fixed monthly repayment to find regardless of how the month has gone. Instead, repayments move with the business’s trading: smaller in the quieter weeks, faster when business is strong. For an owner who needs the funds to clear a tax bill without stalling everything else, that flexibility is the whole point. The total cost is agreed upfront and does not change, with no admin fees or hidden extras added later, and no fixed term to tie the business in. Funds can reach the business’s account in as little as 24 hours.

A merchant cash advance from 365 Finance enables businesses that process card payments to access between £10,000 and £500,000, repaid through a small percentage of future card sales. The approval rate sits above 90%, and no business plan or security is required.

What to Do If a Tax Deadline Is Approaching

If a Corporation Tax or VAT deadline is approaching and working capital is already strained, or likely to be once the payment is made, understanding the options available before the due date can make a significant difference. Leaving it until afterwards tends to do the opposite: it removes the room to act early, narrows the choices that remain, and adds to the eventual cost.

Revenue-based finance such as the facility from 365 Finance is available to UK businesses in this position. The application usually takes only a few minutes, and the assessment is based on actual trading performance that can be tracked directly, rather than the credit score that traditional lenders rely on.

Getting ahead of a tax deadline protects the business’s credit position, avoids HMRC interest charges, and keeps working capital available for the things that move the business forward.