Tax efficient way to park 400k cash?

L'auteur cherche une façon efficace sur le plan fiscal de placer 400k en cash, avec un revenu imposable élevé et une liquidité nécessaire dans 3-4 ans. Il considère déjà de rembourser un prêt à taux élevé et d'investir dans des obligations municipales.

We were planning to upgrade our house last year so gradually liquidated some assets in anticipation for a large down payment. But we had decided to not move until 3-4 years from now. These cash has been parked in my vanguard money market fund getting <4% yield. We are in the 35% tax bucket so the income tax on these interest are significantly. Ideas on other low volatility, liquid and tax efficient options to park 400k cash in this market? Other parameters: 1.5M total liquid asset in brokerage (including the 400k cash), and 1.5M in combined retirement accounts nearly all equity. Primary residence 600k with 300k loan at 3%. A rental with 150k loan at 6.5%. Live in Texas. Not planning to retire in the next 15 years. My instinct would be to pay down the high interest loan and buy municipal ETF like VTEB. But wondering if I’m missing anything