The Shape of the Tax: Mortgage Recording Liability and Transaction Shifting at New York City's 2019 Transfer-Tax Thresholds

New York City's mortgage recording tax assigns borrowers a charge of 1.80–1.925% of the loan, while a purchase without a recorded mortgage incurs no purchase-mortgage recording tax. Applied to 172,633 observed loans, the borrower-side statutory charge averages 1.41% of price for houses and 1.28% for condominiums. New York's 2019 reform created seven transfer-tax thresholds. Comparing prices at the same thresholds before and after the reform, with the unchanged USD 1 million threshold as a control, shows transactions shifting at the new notches that have enough sales to measure. Each shift is larger than the same statistic at any of sixteen never-taxed round prices below USD 6 million, and a year-by-year event study shows it beginning with the reform. Responses do not rise in proportion to the buyer's rate increment, though the estimates do not establish equal responses. A four-borough, USD 300,000–6 million residential purchase-money carve-out totals about USD 246 million annually under fixed transactions and imputed condominium loans. Continuous schedules that raise the same amount from the same transactions are costed for comparison. The paper identifies neither economic incidence nor an optimal tax. Version 2.1 adds placebo-calibrated inference, a year-by-year event study, results by property type and borough, a check that removes foreclosure and lender deeds, and the size of the response in dollars (Sections 5.9 and 5.10). The condominium loans behind the 1.28% figure are now public in a separate linked dataset (concept DOI 10.5281/zenodo.22977532). Files: the manuscript, the supplemental appendix, and paper_in_brief.md, a short non-technical summary. Code and archived analysis inputs are in the separately citable replication package (concept DOI 10.5281/zenodo.22880953). For details of changes between versions, see revision_notes.md.