Most business owners believe they understand who owns what in their companies.

The IRS may disagree.

Under the federal tax code, ownership is not always based on whose name appears on stock certificates or LLC agreements. Through complex “attribution rules,” the IRS can assign ownership to you based on family relationships, business structures, or even stock options you don’t directly control.

And when that happens, the consequences can be expensive.

Let’s break down what you need to know.

What Are IRS Attribution Rules?

Attribution rules are tax provisions that treat you as owning stock or interests that legally belong to someone else. These rules appear in multiple sections of the Internal Revenue Code, primarily:

• Internal Revenue Code Section 267 – Related-party loss disallowance

• Internal Revenue Code Section 318 – Constructive stock ownership rules

• Internal Revenue Code Section 1563 – Controlled group determinations

Each section has a different purpose — but they all rely on the concept of constructive ownership.

In simple terms:
You may be treated as owning stock held by your spouse, children, parents, certain entities, or even trusts — whether you intended to or not.

Why Business Owners Should Care

These rules can quietly affect:

• Deductibility of losses

• Related-party transactions

• Controlled group status

• Eligibility for certain tax benefits

• Application of aggregation rules

• Corporate tax brackets and credit limitations

A routine transaction between family members can suddenly become a disallowed deduction.

Multiple corporations you thought were separate may be treated as one controlled group.

What looked like legitimate tax planning can trigger unintended consequences.

Section 267 – When Losses Get Denied

Under Internal Revenue Code Section 267, losses from sales between related parties are generally disallowed.

This often applies to:

• Sales between family members

• Transactions between an individual and their controlled corporation

• Dealings between commonly controlled entities

Many business owners discover this rule only after assuming a loss deduction that the IRS later denies.

Section 318 – Constructive Stock Ownership

Internal Revenue Code Section 318 is broader and frequently more aggressive.

It determines stock ownership for:

• Corporate redemptions

• Certain reorganizations

• Ownership threshold tests

Here, ownership can be attributed:

• From spouse to spouse

• From parents to children

• From partnerships to partners

• From corporations to shareholders

Even stock options can trigger ownership attribution.

This section is often the technical backbone behind many complex corporate tax determinations.

Section 1563 – The Controlled Group Rules

Under Internal Revenue Code Section 1563, corporations under common control may be treated as a single “controlled group.”

Why does this matter?

Controlled groups must often:

• Share tax brackets

• Allocate certain credits

• Combine limits for deductions

• Apply aggregation rules for compliance testing

If family attribution pushes ownership percentages over specific thresholds, corporations you believed were separate may legally be considered one.

That can significantly affect tax planning.

The Most Common Business Owner Mistakes

Many attribution issues arise from:

• Transferring stock to family members for estate planning

• Creating multiple corporations for asset separation

• Engaging in intercompany sales

• Not reviewing family ownership annually

• Overlooking indirect ownership through entities

The biggest mistake is assuming legal ownership equals tax ownership.

It doesn’t.

Why This Matters More Than Ever

Attribution rules are highly technical — but the IRS applies them mechanically.

They do not care about intent.

They only care about percentage thresholds and defined relationships.

If you:

• Operate multiple businesses

• Work with family members

• Own stock in more than one entity

• Structure buy-sell agreements

• Engage in related-party transactions

You are operating inside the attribution rule framework — whether you realize it or not.

Smart Planning Starts with Awareness

The goal is not to fear attribution rules.

The goal is to plan around them.

With proper structuring, documentation, and annual ownership reviews, business owners can:

• Avoid denied deductions

• Prevent accidental controlled group status

• Structure transactions correctly

• Preserve tax benefits

But ignoring these rules can turn routine decisions into costly compliance problems.

Final Thoughts

IRS attribution rules under Sections 267, 318, and 1563 are not theoretical concepts reserved for large corporations.

They directly impact:

• Family-owned businesses

• Closely held corporations

• Multi-entity entrepreneurs

• Investors with layered ownership structures

If you’re a business owner or tax client with complex ownership — even if it doesn’t feel complex — this is an area that deserves proactive review.

Because when it comes to attribution rules, what you don’t own on paper may still belong to you in the eyes of the IRS.