The 400% cutoff for 2027 coverage is $63,840 for one person, $86,560 for a couple, $132,000 for a family of four. A dollar over and the credit is zero.
The $6,000 senior deduction saves a single 67-year-old $720 and a couple $1,440 in 2026. It is not "no tax on Social Security," and it phases out fast.
If box 3 of your 2025 W-2 tops $150,000, your 2026 catch-up must be Roth. That runs $1,920 in the 24% bracket and $3,600 at ages 60 to 63.
Every SAI calculator online still runs last year's tables. Here's the official 2027-28 formula, a ChatGPT prompt for it, and the entry that costs $10,152.
Leftover 529 money has four exits. The Roth rollover moves one IRA limit a year, so $20,000 takes three years, and cashing out costs 6.6% to 10.2%.