How to Calculate Community Property Income Adjustments: Form 8958

To calculate community property income adjustments on Form 8958, add up each type of community income for both spouses, divide the total in half, and report one half on each spouse’s separate return. Separate income stays with the spouse who owns it. Withholding from community wages is split the same way as the wages themselves, but self-employment tax stays with the spouse who earned it. The form itself is a worksheet: Column A shows the combined total, Columns B and C show what went to each spouse, and B plus C must equal A on every line.

Who Has to Do This

Nine states treat income earned during marriage as belonging equally to both spouses: Arizona, California, Idaho, Louisiana, Nevada, New Mexico, Texas, Washington, and Wisconsin. Alaska couples can opt in by signing a written community property agreement.¹ If you are domiciled in one of these jurisdictions and file married filing separately, federal community property reporting rules apply and Form 8958 is how you show your work. IRS Publication 555 is the controlling guidance.²

Registered domestic partners in California, Nevada, and Washington follow the same allocation rules on Form 8958, but file federally as single (or head of household if they qualify) rather than married filing separately, since they are not treated as married for federal tax purposes.²

Sort Community Income From Separate Income

Before you split anything, decide what actually gets split. Community income includes wages, salaries, and other compensation either spouse earns during the marriage, plus income generated by community-owned property such as rent from a jointly held rental.² Every dollar of community income gets divided equally.

Separate income does not get split. It stays entirely on one spouse’s return. Income counts as separate if it comes from property one spouse owned before the marriage, from a gift or inheritance received by one spouse, or from property the spouses have formally kept separate under state law. State law also controls how earnings on separate property (interest, dividends, rent) are classified, and the answer differs from state to state. The default federal treatment is that separate property produces separate income unless state law says otherwise.²

This is the step people rush. Every allocation error downstream comes from misclassifying an item at the start.

Pull Records for Both Spouses

You cannot allocate what you cannot see. Before opening Form 8958, gather both spouses’ W-2s, 1099s (interest, dividends, self-employment, retirement distributions, and anything else), federal income tax withholding records, and any estimated tax payments made from community funds. Publication 555 directs you to check your state’s rules for dividing estimated payments.³

Missing documents from one spouse make an accurate split impossible, and the IRS compares both returns against combined wage and income records on file. A gap on your side becomes a notice later.

Fill in the Three Columns on Form 8958

Form 8958, “Allocation of Tax Amounts Between Certain Individuals in Community Property States,” has three working columns:⁴

Column A: the combined total from both spouses.
Column B: the amount allocated to the first spouse or partner.
Column C: the amount allocated to the second spouse or partner.

Each income type has its own line. Wages go on Line 1 with a separate row for each employer, interest on Line 2, dividends on Line 3, and so on down the form.³ Enter the combined total in Column A, then split it between B and C. B plus C must equal A on every line.

For community income, the split is 50/50. Combined wages of $120,000 become $60,000 in Column B and $60,000 in Column C, regardless of which spouse’s paycheck the money came from. Federal income tax withheld from community wages splits the same way: half of the total withholding goes on each return, no matter whose W-2 it appears on.³

For separate income, assign the full amount to the owning spouse and enter zero for the other. If one spouse inherited $5,000 that produced $200 of interest, the full $200 goes in that spouse’s column and nothing in the other’s.

When the form is done, transfer each spouse’s allocated amounts to their own Form 1040. Add the two returns together in your head, line by line, and confirm they match the Column A totals. A mismatch between the two returns is one of the most common triggers for IRS follow-up.

Self-Employment Income Splits, Self-Employment Tax Does Not

This is the exception people miss. The net profit from a sole proprietorship may be split 50/50 between the two returns for income tax purposes, but self-employment tax stays entirely with the spouse who actually operates the business.⁵

The same rule covers partnership income. If one spouse’s share of partnership profits is community income under state law, that entire share still counts toward that spouse’s self-employment tax calculation, and none of it shifts to the other spouse for SE tax.⁵ With a combined Social Security and Medicare rate of 15.3% on net earnings, misallocating this line is expensive.

Spouses Who Lived Apart the Entire Year

A special rule can override the 50/50 split on earned income. To qualify, all four of these have to be true:²

You were married at some point during the calendar year.
You and your spouse lived apart the entire year. Temporary absences like vacations do not count as living apart.
You did not file a joint return for a tax year beginning or ending in that calendar year.
Neither spouse transferred any of the earned community income to the other before year-end, aside from small transfers and child support.

When all four are met, each spouse reports their own earned income (wages, salaries, professional fees) as if it were not community income. Trade or business income stays with the spouse who runs the business, matching the self-employment tax rule. Income from community property that is not earned income, such as rental income or investment returns on jointly owned assets, is still divided under state community property law.⁶

Check this rule before you allocate. If it applies, the numbers on Form 8958 look very different.

Allocate Deductions the Same Way You Allocate the Money That Paid Them

If you file separately, deductions have to be divided too. One overriding rule: if one spouse itemizes, the other must itemize as well. You cannot pair one itemized return with one standard deduction return.⁷ The married filing separately standard deduction for 2026 is $16,100.⁸

When both spouses itemize:

Expenses paid from community funds (mortgage interest, property taxes, and other costs paid from a joint account) split equally between the two returns.⁷
Expenses tied to property owned by only one spouse (property taxes on solely owned real estate, for example) go entirely on that spouse’s return, even if the bill was paid from joint funds.⁷
Expenses paid from one spouse’s separate money, such as medical bills paid from a separate account, are deductible only by that spouse.²
IRA deductions are figured separately by each spouse and are not split under community property rules.²

Keep records of who paid each expense and from which account. The IRS expects documentation for every deduction claimed on either separate return.

One thing filing separately does not do is preserve the full slate of credits: the American Opportunity Credit and Lifetime Learning Credit are unavailable to separate filers, and the child tax credit phase-out begins at $200,000 of AGI on a separate return rather than $400,000 on a joint one.²⁹ Publication 555 recommends calculating tax both ways before you commit.

Attach the Form and File Both Returns Together

Each spouse attaches a completed Form 8958 to their own Form 1040.¹⁰ E-filing software usually handles the attachment automatically or lets you upload a PDF. Paper filers place Form 8958 directly behind the 1040 and its schedules.

Filing both returns around the same time helps the IRS reconcile the shared amounts. When only one return arrives, the matching process compares it against full employer records rather than the allocated share, and that mismatch can hold up processing for weeks.

Leaving Form 8958 off a return that needs one can produce a notice or an adjustment based on the full wage-record amount instead of your allocated share. If the adjustment creates a balance due, the failure-to-pay penalty is 0.5% of the unpaid amount per month, capped at 25%.¹¹ Interest also accrues daily at the federal short-term rate plus 3%.¹²

1
Justia. Alaska Code Title 34 Chapter 77 – Section 34.77.090 Community Property Agreement
2
Internal Revenue Service. Publication 555, Community Property
3
Internal Revenue Service. Form 8958, Allocation of Tax Amounts Between Certain Individuals in Community Property States
4
Internal Revenue Service. About Form 8958, Allocation of Tax Amounts Between Certain Individuals in Community Property States
5
Office of the Law Revision Counsel. 26 USC 1402 – Definitions
6
Office of the Law Revision Counsel. 26 US Code 66 – Treatment of Community Income
7
Internal Revenue Service. Other Deduction Questions
8
Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026
9
Internal Revenue Service. Child Tax Credit
10
Internal Revenue Service. Answers to Frequently Asked Questions for Registered Domestic Partners and Individuals in Civil Unions
11
Internal Revenue Service. Failure to Pay Penalty
12
Internal Revenue Service. Topic No. 653, IRS Notices and Bills, Penalties and Interest Charges