Startups model revenue obsessively and costs optimistically. Then the boring costs — the ones nobody puts on a pitch slide — quietly compound and the runway shrinks faster than the plan said. Here's what to build into a 2026 forecast before it bites.

Employment costs, if you're hiring

Your first hires are the biggest lever on burn, and the headline salary is never the real cost. Add employer National Insurance and pension contributions and a hire lands at roughly 1.1–1.2× the salary — though the Employment Allowance offsets a chunk of employer NI for most eligible small companies. National Living Wage rises also ripple up your whole lower pay band, not just minimum-wage roles. Model hires at their loaded cost, with real start dates, in your cashflow forecast.

Business rates, if you take premises

Moving out of the spare room into a unit or studio? Business rates are a real recurring cost, and reliefs (like small business rates relief) have thresholds and application steps — they aren't automatic. Budget the rates, and check what relief you qualify for before signing a lease.

The software creep

Startups accumulate subscriptions like lint — a tool here, a seat there, an annual plan that auto-renews forgotten. Individually trivial, collectively a meaningful monthly leak. Two habits: review subscriptions quarterly, and prefer bundled value where it's genuine (FreeAgent, worth up to £330/year, is included free in our packages precisely so it's one less line on the pile).

Energy, insurance and the "obvious" costs

Energy prices remain volatile; professional indemnity and public liability insurance are often contractually required and easy to under-budget; and taxes like VAT arrive in quarters, corporation tax nine months after year-end — lumps that a naive monthly average hides. Put the lumps in the forecast on the actual dates they fall.

The point isn't pessimism — it's visibility

None of this is a reason not to start. It's a reason to forecast honestly, so you're managing your runway instead of being surprised by it. The founders who survive aren't the ones with the lowest costs — they're the ones who saw the costs coming. We build startup forecasts that include the boring lines, and keep them current in FreeAgent so your zero-cash date is always a known number. Get started from £49 + VAT a month.