• Income tax brackets: IRS Revenue Procedure 2025-32 (Oct 9 2025), made permanent by One Big Beautiful Bill Act (Jul 4 2025)
• Standard deduction: Single $16,100 / MFJ $32,200 / HOH $24,150 (IRS IR-2025-103)
• Age 65+ add-on: $2,050 unmarried / $1,650 married per qualifying person (IRC §63(f))
• OBBBA senior bonus: $6,000/person, phases out $75K–$175K single, $150K–$250K joint (IRS OBBBA deductions page)
• OBBBA tip/overtime deductions: IRS OBBBA deductions page — available 2025-2028
• FICA rates: IRS Topic 751 + IRS Pub 926 + SSA.gov FAQ (Jan 2026) — SS 6.2% up to $184,500; Medicare 1.45% unlimited; Additional Medicare 0.9% above $200K/$250K
• Not modeled: State/local taxes, AMT, NIIT (3.8%), capital gains rates, child tax credit, EITC, self-employment tax, SALT deduction changes. For a complete picture, use IRS.gov tools or a licensed CPA.