Your underwriting model shouldn't die at closing

A deal gets underwritten carefully. Unit-by-unit rents, a renovation schedule, an expense build-up, a debt structure, an exit assumption. Weeks of work, argued over in an investment committee, and ultimately the basis on which capital was committed.

Then the deal closes, and the model is never opened again.

Why the model gets abandoned

It is rarely a decision. It is a consequence of where the model lives.

The underwriting is a spreadsheet. The actuals are in the accounting system. Comparing them means exporting a trial balance, mapping accounts to model line items, aligning periods, and rebuilding a comparison that nobody owns. It is a few hours of work every month — for a report that is not due to anyone.

So it slips. It becomes an annual exercise, then something done only when an investor asks, then something reconstructed under pressure during a refinancing or a sale.

What gets lost

The underwriting is the most useful benchmark an asset has, and it is the only one that reflects why you bought it.

Budget-versus-actual tells you whether you are hitting the plan you set in December. Underwriting-versus-actual tells you whether the thesis is intact. Those are different questions, and the second one is the one investors are actually asking.

Without it, divergence is discovered late. A renovation programme running two months behind, a rent premium coming in at half of what was modelled, expenses tracking above underwriting from the first quarter — each of these is manageable if seen in month three and structural if seen in month eighteen.

Keeping the model alive

The fix is not discipline. It is removing the export step.

If the underwriting is built in the same system that holds the books, actuals post against assumptions continuously. Variance becomes a standing view rather than a monthly exercise, which means people actually look at it, which means divergence surfaces while it is still small.

In practice this means a few things:

The model is attached to the property, not to a file. It survives the analyst who built it leaving.

Assumptions are line items, not cell references. Modelled rent, modelled expense, modelled capital spend — each mapped to the accounts that will record the actual, once, at closing.

Re-forecasting is recorded rather than overwritten. When the plan changes mid-hold, the original underwriting is still there. Otherwise every asset eventually appears to be performing to plan, because the plan keeps moving.

The comparison is available to whoever needs it. Asset management, investor relations, and the lender covenant check are all looking at the same variance.

A reasonable objection

Underwriting in a platform rather than a spreadsheet means giving up some flexibility. Spreadsheets are unmatched for exploring an unusual structure quickly, and no product will fully replace that during diligence.

The argument is not that modelling should never happen in a spreadsheet. It is that once the deal is done, the assumptions you committed to should be recorded somewhere durable, next to the actuals that will be measured against them — so the question “is this asset doing what we said it would” has an answer available on demand, for the whole hold period.