Oregon Corporate Activity Tax (CAT) for Small Businesses: Who Registers, Who Files, and How the 35% Subtraction Works

2026-10-09 · RKube Services

How the Oregon Corporate Activity Tax works for small businesses: the $750,000 registration trigger, the $1 million filing threshold, the 35% subtraction and a worked example.

Oregon has no sales tax, and a lot of owners in Portland and Eugene take that to mean the state leaves gross receipts alone. It doesn't. Since 2020, Oregon has charged the Corporate Activity Tax, a tax on gross receipts that applies to almost every kind of business: sole proprietors, LLCs, S corporations, partnerships and C corporations alike. The name says "corporate," but the entity type barely matters. What matters is how much Oregon commercial activity you have.

Most small businesses never owe a dollar of CAT. The ones that do usually find out late, after they've crossed $750,000 in Oregon sales and missed a 30-day registration window that carries its own penalty. This guide follows one business, a Portland coffee roaster, through a full year: the registration trigger, the filing threshold, the 35% subtraction, the tax itself, and what changes if the business doubles.

Three numbers to remember

The Oregon Department of Revenue's CAT page sets three separate thresholds, and owners mix them up all the time:

1. $750,000 of Oregon commercial activity in a calendar year: you must register for the CAT within 30 days of crossing it.
2. More than $1 million of Oregon commercial activity: you must file a CAT return.
3. More than $1 million of taxable Oregon commercial activity (after the subtraction): you file and pay.

So it's possible to register and owe nothing, and to file a return and still owe nothing. Each line is its own obligation.

What counts as "commercial activity"

Commercial activity is your total gross receipts from transactions and activity in the regular course of business, sourced to Oregon. Think of it as top-line revenue, before any expenses. Sales delivered to customers outside Oregon are excluded, which is why the threshold is about Oregon activity and not your total revenue.

The DOR lists several exclusions. Among them:

• Receipts from sales of items or services delivered outside Oregon
• Wholesale and retail sales of groceries
• Receipts from motor vehicle fuel sales
• Amounts an agent collects for a principal beyond the agent's own fee or commission
• Transactions between members of the same unitary group
• Distributive income received from a pass-through entity

That last item matters for holding structures. If your LLC owns a share of an operating partnership, the income you receive from it isn't counted again on your own CAT return.

The full exclusion list lives in the statute (ORS 317A.100). If your business sells groceries, fuel, farm products or works as an agent, read it closely before you assume you're over the line.

Worked example: a Portland coffee roaster

Say a roaster in Portland sells beans wholesale to cafes and online to customers. In 2026 the numbers look like this:

Step 1: registration

The roaster crosses $750,000 of Oregon commercial activity in late June. From that date it has 30 days to register with the DOR. Registration runs through Revenue Online, and it's a one-time step. If it misses the window, the penalty for failing to register is $100 a month, up to $1,000 per calendar year (ORS 317A.131).

Step 2: is a return required?

Oregon commercial activity is $1,500,000, more than $1 million. A return is required.

Step 3: the 35% subtraction

Before the tax is figured, Oregon lets the business subtract 35% of the greater of two figures:

• Cost inputs, which is essentially cost of goods sold, or
• Labor costs, which is total compensation to employees, excluding payroll taxes and excluding any pay above $500,000 to a single employee.

You pick the larger base. For the roaster, cost inputs ($700,000) beat labor ($500,000), so:

35% x $700,000 = $245,000

There's no subtraction for costs tied to excluded receipts, and none for transactions inside a unitary group. If the business also sells outside Oregon, the cost inputs or labor costs may have to be apportioned under OAR 150-317-1200, so only the Oregon share counts.

Step 4: taxable commercial activity

$1,500,000 minus $245,000 = $1,255,000 of taxable Oregon commercial activity.

Step 5: the tax

The CAT is $250 plus 0.57% of taxable commercial activity above $1 million.

• Amount over $1 million: $1,255,000 minus $1,000,000 = $255,000
• 0.57% x $255,000 = $1,453.50
• Add $250: $1,703.50 for the year

That's the full CAT bill on $1.5 million of Oregon sales. It isn't huge, but it's money the owner didn't plan for, and it arrives on top of the federal return, the Oregon income or excise return, and in Portland, the city and county business taxes.

Step 6: estimates?

Quarterly estimated payments are required when expected CAT liability is $5,000 or more. The roaster's $1,703.50 is under that line, so it simply pays with the annual return.

What changes when the business doubles

Now picture the same roaster three years later, after opening a second roasting site in Eugene:

Labor is now the bigger base. 35% x $1,400,000 = $490,000. Taxable commercial activity is $3,000,000 minus $490,000 = $2,510,000.

• Over $1 million: $1,510,000
• 0.57% x $1,510,000 = $8,607
• Plus $250: $8,857

Two things change at this level.

First, estimates kick in. With an expected liability of $5,000 or more, the business pays quarterly. For a calendar-year taxpayer, the due dates are April 30, July 31 and October 31 of the tax year, then January 31 of the following year. To avoid the underpayment penalty, the installments must cover at least 90% of the year's tax. Short payments draw a 5% penalty. For tax year 2026, the dates are April 30, 2026, July 31, 2026, October 31, 2026 and January 31, 2027, each moving to the next business day when it lands on a weekend.

Second, the choice of base flipped from cost inputs to labor. A growing service-heavy business often sees this happen. It's worth recomputing both bases every year rather than carrying last year's choice forward.

Deadlines and extensions

The CAT return is due on the 15th day of the fourth month after the tax year ends. For a calendar year, that's April 15. A calendar-year business filing for tax year 2026 has a due date of April 15, 2027. If the date falls on a weekend or holiday, it moves to the next business day.

For tax years beginning on or after January 1, 2024, Oregon allows a seven-month filing extension without showing cause. If you already have a federal extension, the CAT extension follows automatically. If not, file Form OR-EXT-CAT by the original due date.

An extension gives you more time to file. It doesn't give you more time to pay. Interest runs from the day after the original due date.

One practical detail trips people up: the CAT return can't be filed through Revenue Online. It goes by mail or through an approved e-file vendor, so check that your tax software actually supports it before the deadline week.

Penalties, in plain terms

The DOR's penalty schedule for the CAT:

• 5% of the unpaid tax if you don't pay by the original due date
• 20% if the tax is unpaid and the return is more than three months late
• 25% of any deficiency if you don't file within 30 days of a demand notice
• 100% for not filing three years in a row
• $100 per month, up to $1,000 a year, for not registering

Total penalties are capped at 100% of the tax. Interest is separate.

Groups of related companies

If you own several businesses that operate together (shared management, shared ownership above 50%, common operations), Oregon may treat them as one unitary group. A unitary group registers, files and pays as a single taxpayer under ORS 317A.106. One member is named the designated CAT entity and files a combined return with Schedule OR-AF-CAT listing the affiliates.

This works both ways. Sales between group members drop out of commercial activity, which helps. But the $1 million threshold applies to the group, not to each company, so three related LLCs at $600,000 each are a $1.8 million taxpayer.

How the CAT fits next to your other Oregon taxes

The CAT doesn't replace anything. A Portland S corporation with $1.5 million in Oregon sales might owe, in the same year:

• The CAT
• The Oregon S corporation return (Form OR-20-S) with its $150 minimum excise tax
• The Portland Business License Tax and Multnomah County Business Income Tax on the combined return
• Payroll filings on Form OQ each quarter

The CAT is deductible as a business expense on the federal return, but it's not deductible against the Oregon corporate excise or income tax. Plan cash flow with all of these in view, not one at a time. For the payroll side, our first-employee payroll checklist covers the federal setup that sits under Oregon's Form OQ. And if you also sell into other states, our guide to sales tax nexus for online sellers explains the opposite problem: states that do have a sales tax.

Bookkeeping that makes the CAT easy

Most CAT pain is a records problem. Owners who struggle at filing time usually can't answer one of these questions quickly:

• How much of this year's revenue was delivered inside Oregon?
• What's our cost of goods sold to date, and what's total compensation?
• Have we crossed $750,000 yet, and on what date?

If your books tag sales by ship-to state and keep cost of goods sold separate from operating expenses, the CAT is a short worksheet. If they don't, it's a weekend of digging through invoices. We'd suggest a monthly check of Oregon commercial activity once you pass about $500,000, so the registration date doesn't sneak past.

Frequently asked questions

Does an Oregon sole proprietor or LLC owe the CAT?

Yes, if Oregon commercial activity is over the thresholds. The CAT applies to nearly every business form, not just corporations.

I'm based in Washington and sell to Oregon customers. Do I owe the CAT?

Possibly. The CAT looks at commercial activity sourced to Oregon, not where you're located. Out-of-state sellers with enough Oregon receipts can have to register and file.

If my Oregon commercial activity is $900,000, what do I file?

You register (you're over $750,000), but you don't file a return because you're not over $1 million.

Can I take both the cost inputs and the labor subtraction?

No. You take 35% of whichever is greater, not both.

When are CAT estimates due for a calendar-year business?

April 30, July 31 and October 31, then January 31 of the next year, when expected liability is $5,000 or more.

Is there a 2026 rate change?

The DOR page doesn't list one. The rate is still $250 plus 0.57% of taxable commercial activity over $1 million. Check the page before you file, since the legislature has adjusted the CAT before.

Where RKube fits

We keep the books and prepare business tax returns for small businesses across the US, including Oregon companies in Portland, Eugene, Salem and Bend. For CAT clients, that means sales tracked by ship-to state, cost inputs and labor costs ready at year end, a reminder when you approach $750,000, and estimate planning once the tax tops $5,000. If you'd like a second look at where you stand, start with a free scoping call and our 30-day bookkeeping trial. Call (984) 234-7030 or visit rkubeservices.com.

General information, not tax or legal advice. Figures are from the Oregon Department of Revenue as of October 2026; check the official CAT page and ORS chapter 317A before you file.