Born on January 1? Social Security treats you as turning 70 a month early — and you should claim by December to get every dollar

If you were born on January 1, 1958, Social Security will consider you eligible for your full age 70 benefit in December 2027 — not January 2028. That means the window to lock in your maximum monthly payment opens a month earlier than your calendar birthday suggests. Claim in December 2027, and your first payment arrives in January 2028. Wait to claim until January 2028, and you’ll miss one month of the highest possible benefit — permanently. Social Security treats anyone born on the first of the month as having been born in the prior month. For you, that makes December 2027 the last and best chance to start benefits at the peak rate. You can apply as early as September 2027, up to four months before your desired start date. When you do, specify that benefits should begin in December 2027. To prevent any misunderstanding, add this to the remarks section: “I do not wish to receive any retroactive Social Security benefits. I want my benefits to become effective with the first month of my age 70 eligibility (December 2027 because I was born on the first of January).” Do that, and your first check arrives in January — with no gap, no delay, and no reduction.