A 529 is a savings account with a tax rule attached. The money grows without being taxed along the way, and withdrawals come out tax-free when they're spent on qualified education costs: tuition, fees, books, room and board for a student enrolled at least half-time, and a limited amount each year toward K-12 tuition. Spend it on something else and the earnings portion gets taxed and takes a 10% penalty. The contributions come back out clean either way, because you already paid tax on those.
Oregon used to let you deduct contributions on the state return. That ended in 2020 and got replaced with a refundable credit, which works differently in a way that matters. A deduction is largest for a high earner. This credit runs the other way: the lower your household income, the higher the percentage of your contribution you get back, and it phases down as income climbs. At the top it flattens to a fixed dollar amount that's the same for everybody.
Refundable is the part people miss. A refundable credit pays out even if you owe no Oregon tax at all. Families who don't itemize and don't owe much are exactly who this was rewritten for.
You don't have to use the Oregon plan to open a 529, but you do have to use the Oregon plan to get the Oregon credit. Other states run good plans with low fees, and a couple of them are cheaper. If the credit is bigger than the fee difference, and for most Oregon households it is, the in-state plan wins on math alone.
The deadline is not December 31. Oregon lets you contribute up to the tax filing deadline in April and count it toward the prior year, which is unusual and useful if you find out in March that you owe. You have to tell the plan which year the contribution belongs to when you make it.
You can also carry a large contribution forward. Put in more than the credit covers in one year and Oregon lets you spread the leftover across the next four returns, so a grandparent making one big deposit isn't stuck taking the credit only once.
What happens if the kid doesn't go to college gets asked every time. Change the beneficiary to a sibling, a cousin, yourself. There's also a newer federal rule that lets unused 529 money roll into the beneficiary's Roth IRA under a set of conditions, including a 15-year account age and a lifetime cap of $35,000. It's narrow, and it takes the worst-case fear off the table.
Credit percentages and the flat amounts get adjusted, so check the current year's figures on the Oregon Department of Revenue site before you write the check. And run it by your tax preparer. I'm an insurance broker, not a CPA.