Through no fault of their own, thousands of Oregonians may have to pay more than they expected to the IRS because of errors by Cover Oregon.

These are people who followed the law, signing up for health insurance as the Affordable Care Act, aka Obamacare, required.

Cover Oregon has identified at least four categories of people who face financial surprises. The latest two categories were revealed last week by The Oregonian’s Nick Budnick, who reported that Cover Oregon used an incorrect formula to calculate tax credits for:

• People who bought policies that include nonstandard benefits such as chiropractic or naturopathic coverage.

• Some people in Marion and Polk counties, depending on which private policies they purchased through Cover Oregon.

Cover Oregon hasn’t said how many people were affected, but Executive Director Aaron Patnode told The Oregonian, “I’m not trying to say this is an insignificant problem. It’s anything other than that.”

Those people will face additional payments to the IRS, or a reduced tax return, because they’ll have to pay back tax credits they received because of Cover Oregon’s mistaken formula. Those repayments are limited depending on a person’s income, Cover Oregon said, but still could total $300 for a family making twice the federal poverty level, and up to $2,500 for families at four times that income level.

Earlier, Cover Oregon had disclosed two other categories of people who might have to pay more:

• About 1,400 were mistakenly enrolled in the Oregon Health Plan, which is the state’s Medicaid program. They might have to reimburse for benefits received.

• Approximately 700-800 people, in contrast, should have been put in the Oregon Health Plan but were instead enrolled in private plans. They might have to repay tax credits they received.

The errors were made by Cover Oregon, but it appears the repayments will be demanded from innocent enrollees. The injustice couldn’t be clearer.

Given that elected state officials are responsible for the errors, all state taxpayers must bear the burden of yet another Cover Oregon fiasco. Voters should not forget it when it’s time to vote.