Mariner's app — which targets people who juggle multi-state residency or do business in various states — would solve a problem that he has dealt with personally several times.
"The app is the reflection of that old saying, 'Necessity is the mother of invention,'" says Mariner, who started traveling frequently from his home in Fort Lauderdale, FL, to New York City when MLB hired him.
"I had the vague notion in my mind that if you spent less than 183 days in New York, they couldn't make you a full-time resident," he says. "What I didn't understand was all the rules and exceptions about how that works."
His misunderstanding led to several letters from the IRS, Mariner says: "I thought myself to truly be a Florida resident — I never changed my voter registration or driver's license. Fast forward to around 2008, I get a notice from New York state saying they want to audit my 2005, '06, and '07 tax returns, questioning my partial residency filing status."
Two years later, it happened again, and Mariner received "a nice little love note saying they want to audit 2008 and 2009."
He discovered that each U.S. state has different rules and regulations that define tax residency.
For example, if you fly from Florida to New York on a Monday night, have meetings all day Tuesday, and fly back to Florida on Wednesday morning, that counts as three days spent in New York, Mariner explains. "In your mind, you're thinking, 'I was in New York for one business day.' In reality, that's three days, because any portion of a day counts."