Check your mailbox: The state Franchise Tax Board is sending out more than 190,000 letters to taxpayers who may owe the state.
The letters, being mailed to both individuals and businesses, are part of the FTB's regular audits of the 2012 tax season.
On Monday, the FTB said it's sending 100,000 letters to individual taxpayers who may have erroneously filed their taxes as "Head of Household."
It's a commonly misunderstood tax-filing status. "We see a high incidence of error because people don't actually read the qualifications," said FTB spokeswoman Denise Azimi, who said about 2 million Californians claim the HOH filing status each year.
Generally, the HOH status is for single taxpayers who have custody of a child or relative. They get a lower tax rate and a higher standard deduction $7,682, instead of the regular $3,841.
Also this month, the FTB is issuing letters to 90,000 California businesses from mom-and-pop stores to large corporations that didn't file a tax return last year for their 2011 income.
"If you hear from us, please respond quickly and fill out the questionnaires," said Azimi. Not everyone receiving an FTB letter will necessarily owe back taxes, she noted, but responding promptly can minimize potential penalties.