Taxes & Paperwork

The forms people forget

None of the rules on the other pages matter if the paperwork behind them never gets filed. This page is a form-by-form reference for the filings tied to Social Security, Medicare, and your retirement accounts — what each one does, and when you actually need it.

RULES CURRENT AS OF 2026

01 Five paperwork tasks to handle deliberately

Start with the plain-English summary in each step below. Click any step to expand the specific forms and where to get them.

The retirement benefits application itself isn't a numbered paper form — you file it online at ssa.gov, by phone, or in person. (Form SS-5 is a different, unrelated form — it's only for getting an original or replacement physical Social Security card, not for claiming benefits.)

Have ready before you apply

Social Security number and birth certificate
Prior-year W-2s or self-employment tax return
Bank account and routing number for direct deposit
Marriage certificate or divorce decree, if claiming spousal, divorced-spouse, or survivor benefits

Form	What it's for	Who fills it out
CMS-40B	Application for Medicare Part B, if you're not automatically enrolled (you're not automatically enrolled unless you're already receiving Social Security benefits when you turn 65)	You
CMS-L564	"Request for Employment Information" — proves you had qualifying employer coverage, required to enroll in Part B during a Special Enrollment Period after leaving a job	Your employer (you submit both together)

If you're already collecting Social Security when you turn 65, you don't need to file anything — Medicare Part A and B enroll you automatically, and your card arrives a few months before your birthday. If you're not yet collecting Social Security, enrollment is not automatic and you need to act during your Initial Enrollment Period.

Retirement income generally isn't withheld automatically the way a paycheck is — you have to opt in, or you may owe a large lump sum (plus possible underpayment penalties) at tax time.

Form	Use it to withhold from	Details
W-4V	Social Security benefits	Choose a flat 7%, 10%, 12%, or 22% withheld from each payment — no other percentages or dollar amounts allowed
W-4P	Pension or annuity payments	Works like a paycheck W-4 — based on filing status and expected income
W-4R	One-time IRA/401(k) withdrawals and rollovers	Default withholding is 10% for a withdrawal you keep (20% is mandatory, not elective, on an indirect 401(k) rollover — see the 401(k) & Savings page)

The beneficiary form on file with your 401(k), IRA, and life insurance provider — not your will — determines who inherits that account. This surprises people constantly.

Your will does not override a beneficiary form. An outdated beneficiary designation (an ex-spouse, someone who's passed away) will be honored over what your will says, in almost every case.

Review and update beneficiary forms after any of these events: marriage, divorce, birth of a child or grandchild, death of a named beneficiary, or simply once every few years as a checkup. Contact each account's custodian directly — there's no single universal form.

Form	Reports
SSA-1099	Total Social Security benefits paid to you last year — needed to figure out how much is taxable (see the Social Security page)
1099-R	Distributions from a 401(k), IRA, pension, or annuity — including RMDs and Roth conversions
1099-DIV / 1099-INT	Dividends and interest from taxable brokerage or bank accounts
1040-SR	An optional version of the standard tax return with larger print, available if you're 65 or older — reports the same information as the regular 1040

Forms and thresholds change. This page names the forms and what they're for, not how to fill them out — always download the current version from the official source (ssa.gov, cms.gov, or irs.gov) rather than an old copy, since form revisions do happen. A tax professional is worth the cost in the years you have unusual events — a Roth conversion, a rollover, or your first year of RMDs.