The Clock You Didn't Underwrite: Subscription Lines and UK Private Equity Returns

In UK private equity, the subscription line has become ordinary plumbing. A fund agrees a revolving credit facility with a bank, secured against investors' unfunded commitments, and draws on it to bridge the gap between an investment and the capital call. The practice is neither new nor inherently troubling. It can reduce cash drag, smooth calls for investors and spare managers from holding large idle balances. But because IRR is a time-weighted measure, anything that changes the timing of cash flows changes the reported return. For UK limited partners comparing managers in 2026, the relevant question is not whether subscription lines exist. It is whether the returns being presented are measured on a clock the LP would recognise.

What the facility actually does

A subscription line sits between the fund and its investors. When the fund needs cash, it can draw from the facility rather than immediately calling capital. The lender is repaid when LPs fund their commitments, typically weeks or months later. The facility is secured by the fund's right to call capital, and its size is usually set as a proportion of unfunded commitments. In a well-run fund, the line is a liquidity buffer. It allows the manager to complete a transaction without forcing a rushed call, and it can help LPs manage their own cash planning. For UK pension schemes, insurers and family offices, that administrative smoothing has genuine value.

The facility is not free. Interest, arrangement fees and commitment fees are fund expenses. They should be borne by investors and reflected in net returns. A line that is cheap relative to the cost of holding cash may be sensible treasury management. A line that is expensive, overused or poorly disclosed is a different matter.

Where the IRR begins to flatter

IRR discounts cash flows to a single annual rate. Move an outflow later and the rate rises, even if the underlying investment is identical. A fund that takes twelve months longer to call capital for the same asset, and exits at the same multiple, will report a higher IRR than a fund that called immediately. The multiple is untouched. The discounting is not.

This is not a theoretical curiosity. If subscription lines are used systematically to delay calls, the headline IRR can look stronger than the economics warrant. The effect is most pronounced in funds with short holding periods and early-stage investments, where the timing of the initial outflow carries more weight. It can also obscure comparisons between vintages, because a manager that adopted a longer draw period in one fund may appear to have improved performance without any change in investment skill.

The industry has recognised the issue. ILPA guidance has encouraged managers to disclose the existence and use of subscription lines, to report performance both with and without the facility effect, and to ensure that facility costs are clearly allocated. That guidance is a useful starting point, but it is not a substitute for LP diligence. Disclosure can be technical, and a single line in a quarterly report is not the same as an honest reconciliation.

Legitimate treasury management versus performance cosmeticism

The distinction is rarely binary, but it is usually visible in policy. A legitimate approach uses the line for short-term bridging, keeps utilisation within a sensible proportion of unfunded commitments, and treats the facility as a cash-management tool rather than a source of permanent leverage. The manager should be able to explain why the line exists, how it is sized, what it costs and how often it is drawn.

A more cosmetic approach tends to show up in patterns. The line is rolled repeatedly. Draw periods stretch beyond ordinary administrative timing. The facility is sized close to the fund's entire unfunded commitment. Performance is reported on a gross basis without clear disclosure of financing costs. The manager resists providing an IRR that excludes the facility effect. None of these practices is automatically improper, but together they suggest that the line is doing more than smoothing cash flows.

UK LPs should also watch for the interaction with distribution practices. A facility used to accelerate a distribution is a different proposition from one used to delay a call. The former may improve reported IRR and DPI in the short term while adding leverage to the fund. The latter mainly shifts the timing of investor outlays. Both need to be understood, and both should be governed by the limited partnership agreement and, where appropriate, the LP advisory committee.

What 2026 adds to the debate

The cost of carry matters more than it did in the low-rate years before 2022. Facilities that looked inexpensive when base rates were near zero are less so now. Lenders are also more selective about the funds they will support, and covenant packages have tightened. A manager that relies heavily on a subscription line is exposing the fund to refinancing risk and to the possibility that a facility is withdrawn or reduced at exactly the wrong moment.

For UK LPs, the practical response is to normalise. Compare managers on metrics that are less sensitive to the timing of calls: TVPI, DPI and PME. Ask for since-inception IRR both with and without the subscription line effect. Look at the average number of days between investment and capital call, and ask whether that number has changed across vintages. If a manager's IRR has improved while its multiples have not, the clock deserves scrutiny.

A practical set of questions

UK LPs can make the conversation concrete with a short list of questions. What is the size of the facility relative to unfunded commitments and net asset value? What is its maturity, and what covenants apply? What is the average draw period, and how has it changed over the fund's life? Are reported IRRs gross or net of facility interest and fees? Can the manager provide an IRR that excludes the facility effect? How are facility costs allocated across LPs and vintages? What happens if the facility is unavailable during a call? And has the LP advisory committee reviewed the policy?

The answers will not always be tidy. Private markets are not a laboratory, and managers need flexibility. But a manager who can answer clearly is more likely to be using the line as a tool rather than a presentation device. A manager who cannot, or will not, is asking LPs to underwrite a clock they cannot see.

Subscription lines are not the problem. Opacity is. In 2026, UK LPs should treat the facility as part of the fund's financial architecture, not a footnote to it. The honest IRR is not necessarily the lower one. It is the one that measures the same cash flows on the same basis, so that performance can be compared and capital can be allocated with confidence.