Sure, Austin revels in its youthful reputation, but a lot of the people coming here are probably not fresh-out-of-college looking to form a band or a startup.

A new look at income migration from the IRS shows that newly-arrived Austinites aren’t as young as previously thought. What’s more, the highest concentration of transplants isn't from either of the tried-and-true drivers of Austin population growth, New York and California. They’re from Florida.

“There’s been some speculation lately that more and more retirees are picking Austin and this data certainly implies that that could be the case,” says Brian Kelsey with Civic Analytics, an Austin-based economic research firm.

The recently-released data tracks where people file their tax returns from one year to the next. He says people that are moving to Travis County are bringing a lot of money with them. In fact, the most recent 2012-2013 data show newly-arrived income in Travis County totaled about $2.3 billion dollars. Kelsey says that means many newcomers are probably older, maybe even retirees.

“If you look around the country at the counties that receive the most higher net worth people. It’s usually those destination retirement counties in Florida and Phoenix,” Kelsey says.

That brings us to the whole “California” thing. People are used to thinking California transplants were driving growth in Austin. Actually, Kelsey says, California’s in third place. New York is in second. The data puts Florida is in first place, for which, Kelsey says, there are a couple of reasons.

“Now we’re seeing Florida kind of coming out of nowhere. That could be something in the methodology that changed, where there was historically an undercount [of people] from Florida and that's been corrected, or it could be that migration is actually increasing,” he says.

Kelsey says one thing’s for sure: People moving here with higher household incomes than the local average are able to pay more for things. That contributes to the local affordability issues we hear so much about.

“You’re going to see that show up in rents, you’re going to see that show up in housing costs,” he says. “And, just generally, it’s going to affect the aggregate amount of income in Austin for everything from discretionary money spent at restaurants to housing costs.”

Kelsey says the IRS plans to release more recent 2013-2014 data before the end of the summer.