Spreadsheet vs sinking fund software: which one keeps your fund honest?

A quantity surveyor's forecast is a careful snapshot. A professional inspects the building, lists the major assets, estimates remaining life and replacement cost, and models contributions over ten or more years. On day one it's the most credible number you'll have.

The problem is what happens on day two. The PDF doesn't know the lift was reclad early, that the painting tender came in 30% over the estimate, or that the committee voted to defer the roof another two years. It can't see the fund balance. It has no idea what you've actually spent. By the second AGM it's a historical document the treasurer quietly works around, and by the fourth year — when you finally pay for the next review — you're often forecasting off figures that stopped matching reality a long time ago.

A spreadsheet fixes one thing the PDF can't: you can edit it whenever you like. That's a real advantage, and for a diligent treasurer it can work for years. But editing it and keeping it *correct* are two different jobs.

Spreadsheets carry a quiet maintenance and error cost. A formula that doesn't extend to the new row. A copy-paste that overwrites an escalation rate. A column that silently stops feeding the total. Nobody notices until the projection is thousands of dollars out and a five-figure decision has already been made on it. And the knowledge usually lives with one person — when they leave the committee, the file becomes a black box nobody dares touch. The spreadsheet doesn't go stale on a fixed schedule like the PDF; it goes stale the first time someone forgets to update it after a job, and stays stale until someone catches it.

A living maintenance plan starts from the same inputs — assets, lives, costs, contributions — but treats the forecast as something that recomputes, not something you re-type. Change a replacement cost or push a renewal date and the whole projection updates instantly, with the escalation and shortfall visible rather than buried in a formula.

The bigger difference is the link to reality. The plan tracks actual spend against forecast, so you can see at a glance whether the fund is tracking, drifting, or heading for a shortfall. When a quote is accepted, the forecast updates automatically — the real number replaces the estimate, and every downstream year recalculates. There's no annual scramble before the AGM, because the plan was never out of date: it's always current, and the figure you present is the figure the system has been keeping live all along.

If you want to feel the difference before committing, the free sinking fund calculator runs the same recompute logic on a single building.

A spreadsheet is genuinely acceptable for a small, simple scheme — think a 2–6 lot block with a short asset list: a roof, some common paint, maybe a fence and a bit of paving. Few assets, infrequent works, and a treasurer who's comfortable in Excel. In that situation the maintenance burden is low, the chance of a costly formula error is small, and the cost of dedicated software may outweigh the benefit.

Be honest about which side of the line you're on, though. Once you've got a lift, a fire system, a pool, intercom, render, or balustrades — anything with staggered renewal dates and serious replacement costs — the spreadsheet stops being simple and the error risk climbs fast. That's the point where a structured tool stops being a luxury and starts being cheap insurance. Our guide to how much should be in a sinking fund can help you judge where your scheme sits.

A quantity surveyor's report is a one-off five-figure expense in many cases, repeated every three to four years — plus the cost of the years it spends out of date in between. A spreadsheet looks free, but the real cost is the treasurer's time and the risk of a single error steering a major decision.

Plinth is $750 per year per account (which includes your first building) and $350 per additional building — a low, predictable annual subscription that keeps the plan live the whole time, not just for a fortnight after a review lands. It doesn't replace professional judgement on a major rebuild, and it isn't meant to. What it replaces is the staleness: the gap between what your document says and what your building is actually doing. For most schemes beyond the smallest blocks, that's the better trade.