Covered California will be open for business this weekend. Sunday is the first day of open enrollment for purchasing 2016 health insurance through the exchange.

Covered California officials said the service center will be staffed and fielding phone inquiries from 10 a.m. to 6 p.m. Sunday.

Interest could run a little higher during this open enrollment period because of impending increases in tax penalties for those without health insurance. For federal tax returns filed in 2016 and beyond, the penalty for not having health insurance will be at least $695 for each adult and $347.50 for each child, up to $2,085 per family. The individual penalty is 2.5% of income or $695 per adult, whichever is bigger.

Penalties could be the stick that moves many Californians toward the carrot dangling at Covered California: federal subsidies that may significantly cut the cost of health insurance for the estimated 750,000 people in the state who qualify for them.

Exchange officials hope they can enroll between 295,000 and 450,000 Californians — roughly half of the eligible pool — into new coverage during this open enrollment period from Nov. 1 till Jan. 31.

The penalty tax has risen every year: from $95 per person or 1% of annual income in 2014 to $325 per adult or 2% of income in 2015. Now it’s $695 per person or 2.5% of annual income, whichever is greater.

Covered California officials on Friday will board a bus for a 29-city tour of California to help drum up interest and enrollees during open enrollment.