Draft — not checked against a real transaction. The rent chain and the cash-flow structure are validated against figures the housing agencies publish; no closed deal has been reproduced in it. What has been validated, and how to check it against a deal you know

Follow the money

Thirty years of an affordable housing project, as plumbing, one milestone at a time. Money is water: taps fill, pipes carry, tanks hold, drains empty. Pipe width is how fast money moved during the stretch you are looking at; the figure on the pipe is how much moved in total, and the figure on each box is the running total to date.

This runs on whatever project you last had open in the screener, so the numbers are yours. The pale part of each tank is what arrived during the current stretch — step forward and it settles into the solid fill. Everything for a step is inside the diagram: what happens, who holds what, and what moved. Maximize fills the screen with it.

Arrow keys work too. Every figure belongs to the stretch between the previous milestone and this one.

What to watch for

Each note lights up when the current stretch covers the months it describes. Hover or focus one to read it at any time.

  1. Almost all the money arrives before anyone moves in

    Four taps open at once and everything drains into construction. By the time the first resident arrives, most of the money that will ever enter this project has been spent, and the brickwork is complete.

    That is why the moment to ask for things is early — while the budget is still being written. After closing, the answer becomes no not out of bad faith but because there is nothing left to move.

  2. Lease-up is where projects die

    The building opens with the running-costs pipe already at full width while the rent pipes are still thin. The building is paying staff, insurance and taxes on an almost empty property.

    This is the thinnest moment in thirty years. It is why lenders require reserves, and why an under-funded project fails here rather than later.

  3. The paperwork is load-bearing

    Two thin dashed lines carry no money at all: income certifications from residents to the building, and compliance reports from the building back to the agency along the bottom of the diagram.

    They are drawn because without them nothing else happens. If certifications are not collected and reports are not filed, the units stop counting, the credits stop, and the investor's money — already spent — is clawed back. Documentation is as good as cash here, because the cash does not come without it.

  4. The rent does not go to the investor

    This one catches almost everybody. The investor owns 99.99% of the partnership, so it looks as though they should receive nearly all the cash. They do receive nearly all the tax items — the credits and the depreciation losses. Cash is distributed under a separate waterfall.

    Follow the pipes leaving the building: running costs, debt service, reserves, and then a thin residual that mostly repays the developer's deferred fee. Most projects of this kind expect to pay the investor essentially no cash at all, ever.

    So the rent your neighbours pay is not the investor's return. Their return is the credit pipe on the far left, and it is finished by year ten.

  5. The pipe that never touches the building

    Top left: credits go from the government straight to the investor. They never enter the building and never pay for anything in it. That single pipe is why a private investor funds housing that is not designed to make a profit.

    For a community negotiating with a developer, this changes the shape of the argument. Asking for lower rents is not taking money out of someone's pocket in the way it can appear — it is changing how much subsidy the project needs.

  6. After year ten, and after year fifteen

    The credit pipe closes at year ten — the investor has received everything they came for. The affordability obligation runs to year fifteen, and usually to year thirty by agreement.

    Year fifteen is when the investor exits and ownership can change. What happens then is worth agreeing at the beginning rather than in year fourteen: some projects transfer to a non-profit or a community land trust at that point.