Income tax, capital gains, Roth conversions, tax-loss harvesting, and state taxes.
Long-term gains (held over one year) are taxed at preferential rates of 0%, 15%, or 20%
The 401(k)/403(b) employee deferral limit is $23,500 in 2026; +$7,500 catch-up at 50+; +$11,250 super catch-up at 60-63 (no other ages)
The U.S. federal income tax is progressive — higher income is taxed at higher rates
A Roth conversion moves pre-tax money into a Roth account, triggering income tax now
AGI is your gross income minus a specific list of "above-the-line" adjustments
A conversion ladder spreads Traditional-to-Roth conversions across multiple years
RSUs are taxed as ordinary income when they vest; NSOs when you exercise (on the bargain element)
The five statuses are Single, MFJ, MFS, HoH, and QSS
Use-it-or-lose-it is no longer absolute — most plans now allow carryover OR a grace period (employer picks one, never both)
Marginal rate is what the next dollar you earn will be taxed at
The "after-tax 401(k)" slot lets you contribute up to the § 415(c) total — $72k in 2026 — beyond the regular employee + employer caps
NIIT is a 3.8% surtax on investment income above the MAGI threshold ($200k single / $250k MFJ — not inflation-indexed)
If you owe more than $1,000 in tax beyond what's withheld, you owe quarterly estimated payments
SE tax = 15.3% on net self-employment earnings (12.4% Social Security up to the wage base + 2.9% Medicare with no cap)
The dividing line is one year plus one day
2026 standard deduction is $16,100 single / $32,200 MFJ
State income tax rates range from 0% to over 13%
At death, heirs' basis in inherited assets resets to fair market value
Realize losses to offset gains, reducing current-year tax
AMT is a parallel tax system that disallows some deductions and applies its own brackets
HSAs are the only account that's tax-deductible going in, tax-free growing, AND tax-free coming out (for medical) — no other vehicle has all three
The 2025 OBBB added a $6,000 above-the-line deduction for filers age 65+ (each spouse if both qualify in MFJ)
QBI is a 20% deduction on qualified pass-through business income — sole props, partnerships, S-corps, some rental
The SALT cap limits how much state + local tax you can deduct on your federal return
Buying substantially identical security within 30 days of a loss sale disallows the loss