The One Big Beautiful Bill Act (OBBBA, Public Law 119-21) was signed on July 4, 2025, and it locked in most of the 2017 Tax Cuts and Jobs Act for good. Child support doesn’t have a line item in the bill, but because the guideline formula runs on after-tax income, anything that moves your taxes moves your support number. Four changes do the work for 2026.

Permanent federal brackets

The TCJA rates (10%, 12%, 22%, 24%, 32%, 35%, 37%) are now permanent. Had OBBBA not passed, the brackets would have snapped back to their higher pre-2017 levels in 2026. That reversion would have raised taxes and cut into net disposable income for both parents, so keeping the lower rates props up the income the formula sees.

A bigger SALT cap

The cap on deducting state and local taxes sat at $10,000 under the TCJA. OBBBA raised it:

  • $40,400 for most filers (single, head of household, married filing jointly)
  • $20,200 for married filing separately
  • Phasing back down to $10,000 for high earners (MAGI above $505,000)

This is a California story as much as a federal one. Between property taxes and a high state income tax, plenty of Californians blew past the old $10,000 cap and lost the rest. A higher cap lets more of those state taxes come off federally, which lowers the federal bill and nudges net disposable income up.

A larger Child Tax Credit

The credit climbs from $2,000 to $2,200 per child, phasing out at $200,000 of income for single and MFS filers and $400,000 for MFJ. It’s now indexed to inflation, so it will keep drifting upward instead of staying frozen.

Permanent standard deductions

The larger standard deductions stick around too:

  • Single / MFS: $15,000
  • Head of household: $22,500
  • MFJ: $30,000

What it adds up to for support

For most parents the changes pull in the same direction. Permanent TCJA rates mean lower federal tax and a higher net. The roomier SALT cap adds a bit more net for itemizers in high-tax California. The larger Child Tax Credit cuts federal tax further for whoever claims the kids. Net disposable income rises, and since the formula divides up after-tax income, a higher earner with more net generally lands on a higher support figure.

The Support Split calculator already runs on the 2026 federal and California brackets, the new SALT rules, and the updated Child Tax Credit as OBBBA enacted them, so every result reflects the law as it stands now.