Sign-up season started Sunday for health insurance under the Affordable Care Act, or Obamacare, now in year 3.

Premiums are going up an average of 7.5 percent, but they could be much higher depending on where you live.

Self-employed accountant Fred Imel of Oklahoma buys insurance for his family through the Health Insurance Marketplace.

Self-employed accountant Fred Imel of Oklahoma. CBS News

He just learned his premiums are going up from $1,100 per month, to $1,700.

That means Imel could pay $20,000 next year for health insurance -- an increase of 66 percent.

"The first job when I got out of school was $16,500," Imel said. "You know that's a lot of money."

The Affordable Care Act requires every state to set up a marketplace for the uninsured or allow the federal government to do so.

But when some insurance providers back out of that market place, as some did in Fred Imel's state, consumers pay more.

Premiums vary widely -- and are actually decreasing in a few places. Indiana is down 12.6 percent, and Mississippi is down 8 percent. But in most states, premiums are rising, up 31.5 percent in Alaska and up nearly 36 percent in Oklahoma.

Elisabeth Benjamin, who helps people get health care coverage, said there are many reasons for the changes.

"That could be because of market consolidation, could be providers asking for more money or drug prices going up," Benjamin said. "There is this clause that if your rate increases over 10 percent you should be scrutinized by regulators."

According to the Department of Health and Human Services, with tax credits, more than 7 in 10 current market place enrollees could find plans for $75 per month in premiums, or less.

But Fred Imel doesn't qualify for tax credits, forcing him to shop around.