About Us

The Full Duplex Systems Story

Full Duplex Systems Inc is now celebrating its 20th year, having been founded in the early nineties when John Brantley began to develop commercial tax software and sell electronic filing services as an adjunct to his tax practice. The tax software and electronic filing side of the business was sold in 2005, so John is now a full-time tax practitioner again along with being involved part time in a separate internet development business with his son.

John grew up in Woodstock, Maryland, and still lives nearby. He graduated with an MA from Johns Hopkins University and worked for 7 years as a regional manager for Tax Computer Systems before going into business for himself. He’s been enrolled to practice with the IRS for 28 years. He’s passionate about his work and just as passionate about gardening, classical music, wine, carpentry, literature, history and his family. He’s a pretty fair golfer as well.

Full Duplex Systems List of Services

  • Personal, Business & Estate Tax Return Preparation
  • On-Line Consulting Services
  • Tax & Financial Planning
  • Estate Planning
  • Small Business Formation
  • Retirement Plans & Employee Benefit Planning