
Fifteenth is a tax technology company that simplifies complex personal taxes through a combination of human expertise and predictive technology. The company offers unlimited tax advisory and year-round planning with a dedicated team, leveraging Taxcasting technology to provide clients with clear visibility into their total tax picture and predictions of tax obligations. Fifteenth automates document collection and integrates with banking and investment platforms to streamline tax management. Its business model is based on personalized, flat-fee pricing that covers strategy, planning, and filing, targeting high-net-worth individuals, investors, and tech professionals with complex tax situations such as stock options and multiple K1s. The company emphasizes security with encrypted data storage and strict access controls, positioning itself as a trusted partner for professionals seeking proactive and hassle-free tax services.

Fifteenth is a tax technology company that simplifies complex personal taxes through a combination of human expertise and predictive technology. The company offers unlimited tax advisory and year-round planning with a dedicated team, leveraging Taxcasting technology to provide clients with clear visibility into their total tax picture and predictions of tax obligations. Fifteenth automates document collection and integrates with banking and investment platforms to streamline tax management. Its business model is based on personalized, flat-fee pricing that covers strategy, planning, and filing, targeting high-net-worth individuals, investors, and tech professionals with complex tax situations such as stock options and multiple K1s. The company emphasizes security with encrypted data storage and strict access controls, positioning itself as a trusted partner for professionals seeking proactive and hassle-free tax services.
What they do: AI-enabled personal tax advisory and filing for individuals with complex tax situations (equity, multiple K-1s)
Business model: Flat annual fee covering year-round planning, strategy, and filing
Target customers: High-income professionals, investors, and people with equity compensation
Recent fundraising: Seed — $8.25M announced Feb 10, 2025
Personal tax complexity for high‑income individuals and those with equity compensation
2024
Tax technology / Personal finance
$8,250,000
“Includes institutional lead investors (General Catalyst, A*) with additional participation from angel/seed investors (SV Angel, Karman Ventures, others)”