Your forecast said $340 a week. Your bank statement says something else.
- Forecasts drift from small gaps: partial vacancy, a fee that's 8.8% not 8%, an insurance renewal that jumped 22%.
- A $1,400/year shortfall doesn't surface unless you're comparing forecast to actual, line by line.
- Catching a rent shortfall in month two leaves ten months to adjust. Catching it at tax time leaves nothing.
- The useful question isn't 'did I make money?' It's 'where did the forecast and the account diverge, and when?'
Every forecast looks clean on the day you build it. The gap shows up the first time you line it up against a real bank statement.
Where the drift usually comes from
It’s rarely one big miss. It’s a handful of small, specific gaps that compound:
- Vacancy that didn’t make it into the model. A three-week gap between tenants doesn’t show up in a forecast built on 52 weeks of rent, but it shows up in the account balance.
- The management fee that’s actually 8.8%, not the round 8% used in the spreadsheet. Small on paper, real over a year.
- An insurance renewal that jumped 22% year on year. Forecasts built once at settlement rarely get revisited when a renewal notice lands twelve months later.
- A rates bill charged quarterly, not annually. The number’s the same either way, but the timing isn’t, and a forecast that assumes one annual hit can make a quarter look worse than it is.
None of these are forecasting errors exactly. They’re the normal gap between a projection built with reasonable assumptions and what a property actually does once it’s tenanted.
A worked example
A property forecast at $650 a week rent and $9,000 a year in operating expenses looks straightforward on day one.
Six months of actuals tell a different story: average rent across the period comes in at $625 a week, pulled down by one three-week vacancy between tenants. Operating expenses are tracking at an annualised $9,800, mostly from an insurance renewal that came in higher than budgeted.
Net effect: the property is running about $1,400 a year worse than the original forecast. That’s not a disaster, it’s exactly the kind of gap forecasting is supposed to surface, but only if someone’s actually comparing the two.
Why monthly beats annual
The value of a forecast isn’t that it’s right on day one. It’s that it gives you something to check reality against, and the earlier you check, the cheaper the correction is.
Catch a rent shortfall in month two and you’ve got ten months left in the year to adjust, top up the shortfall, or have the conversation with your property manager about why the fee crept up. Catch the same gap at tax time in month fourteen and you’re explaining a surprise to your accountant instead of a small correction you made months ago.
What to actually reconcile
The useful comparison isn’t “did I make money this year.” It’s line by line: rent received against rent forecast, each expense category against its budgeted line, month by month rather than annually. The insight report in prop-insights.app is built around this comparison — forecast against actual, updated as the numbers come in, so the gap doesn’t quietly compound between now and tax time. That’s what turns a forecast from a one-time guess into something that keeps a portfolio honest.