@unpublished{sotomayor2026tipping,
  title  = {Tipping the Tax: How Government Surcharges Become Gratuities},
  author = {Sotomayor, Tyler and Uceda-Sosa, Gabriel},
  year   = {2026},
  month  = jul,
  note   = {Working Paper, Columbia University},
  url    = {https://tylersotomayor.com/research/tipping-the-tax/}
}