The Execution-Certainty Wedge: Allocation, Distribution, and the Design of Housing-Market Instruments

Buyers who can close with certainty, usually cash buyers, can win homes over buyers who value them more. This paper asks what that does to who gets housing and which policy instruments could change it. It compares acquisition caps, fair-share quotas, constant charges and contention-triggered duties in a stylised agent-based housing market, with instruments tuned on one set of seeds and evaluated on another. At full-run access targets, a constant charge preserves more buyer value than the signal-based duty and gives slightly smaller access gains. Following entering cohorts until they resolve changes the comparison: the two charges are close near a five-point access gain, and the signal duty has a small value advantage near ten points. Distributional weights, endogenous listings and the choice of efficiency benchmark all qualify the ranking. New York City evidence motivates the application but does not identify a corrective rate. The companion estimate of the cash–mortgage price gap depends heavily on who pays cash: when a company buys with cash the gap is close to zero, and for other cash buyers it roughly halves once possible transfers between relatives are set aside. Much of the observed cash discount therefore reflects who the buyers are, not what closing certainty is worth. The results omit strategic bidding, renter welfare and administrative costs, and they are not a calibrated policy evaluation. Version 5.1 aligns the empirical sections with the current companion papers. No simulation result changed. For details of changes between versions, see revision_notes.md. Companion papers: Who Gets the House? (doi:10.5281/zenodo.22421850), The Shape of the Tax (doi:10.5281/zenodo.22925301) and When a Deed Is Not a Market Sale (doi:10.5281/zenodo.22925383).