Short answer: keep the records that show what you paid for an investment (trade confirmations, purchase statements, records of reinvested dividends and stock splits) for as long as you own it, and then until the IRS period of limitations ends for the tax year you sell it, generally three years after you file that year's return. Keep Form 1099-B and the other year-end tax forms with that year's return. Routine monthly statements have no official retention rule; a common practice is to keep them until the year-end statement arrives and agrees.

Everything else is detail around one idea: the IRS taxes your gain, and your gain depends on your cost, so the proof of cost is the record that has to survive. For other kinds of documents, the master retention chart has the quick answer.

Investment records at a glance

Document Keep for Why / source
Trade confirmations and purchase records While you own the shares, then until the limitations period ends for the year you sell IRS property rule; Publication 17 says records should show purchase price and commissions
Records of reinvested dividends and stock splits Same as the purchase records Publication 17 lists them as part of your investment records
A separate record for each lot bought at a different time Until every share from that purchase is sold Publication 550
Form 1099-B, 1099-DIV and other year-end tax forms With that year's return, generally 3 years after filing IRS general rule
Monthly and quarterly statements No official rule; practice is until the year-end statement checks out Unless a statement is your only proof of a purchase
Records supporting a worthless-securities loss 7 years IRS: 7 years if you claim a loss from worthless securities
Retirement and pension plan documents Forever FTC: keep forever

This is what's generally true for federal taxes in the US, not tax advice. For anything with real money attached, check the IRS publications or ask a professional.

Why cost basis is the record that matters

Publication 17 says your investment records "should show the purchase price, sales price, and commissions," and may also show reinvested dividends, stock splits, load charges and original issue discount. Each of those changes your basis, the number the IRS subtracts from the sale price to find your gain.

Reinvested dividends are the classic trap. Each one quietly buys more shares, so it adds to what you paid. Forget them, and your records understate your basis, which makes your gain look bigger than it was.

The clock rule comes from the IRS's general guidance on property: keep the records "until the period of limitations expires for the year in which you dispose of the property." A fund you bought in 2009 and sell in 2030 needs its 2009 purchase record into the mid-2030s. That's why "seven years" doesn't work as a rule for investments. The guide to how long to keep tax returns covers the longer IRS windows, such as six years when more than 25% of income was left off a return.

Covered and noncovered securities

Brokers now do a lot of the bookkeeping. Publication 550 says that if you sold a covered security, "your broker should send you a Form 1099-B that shows your basis," and that a covered security is generally one "you acquired after 2010, with certain exceptions."

Noncovered securities, mostly older purchases, are "not subject to added reporting by your broker." Publication 550 doesn't say it in so many words, but the consequence is plain: for shares bought before 2011, your own records may be the only place the basis lives. If you hold anything that old, find those records now rather than at the moment you sell.

Shares bought at different times

If you bought the same fund in 2015, 2018 and 2022, those are three separate purchases at three different prices. Publication 550 says to keep a separate record of each purchase "until all shares purchased at the same time have been disposed of completely." Selling the 2015 shares doesn't free you from the 2022 record.

Gifted shares need someone else's records

Receive shares as a gift and you take on the giver's history along with them. Publication 550 says you must know the donor's adjusted basis just before the gift, the fair market value when you received it, any gift tax paid, and the date of the gift. The easiest time to get those numbers is the day you receive the shares, while the giver still remembers and can find their statements.

Which statements to keep and which to shred

Monthly statements are mostly a running record of things you'll see again on the year-end statement. There's no official rule for them. A common practice is to check each month for errors, keep the year-end statement, and shred the monthlies once it agrees, unless one of them is your only proof of a purchase. The document retention entry explains how these keep-or-shred decisions work in general.

Two practical habits help. Download statements as PDFs while you still have a login: before you close an account, move it to another broker, or lose access for any other reason. And keep retirement and pension plan documents for good; the FTC lists "retirement and pension plans" in its keep-forever group.

Where to keep investment records

The manual way on iPhone. Download each confirmation and year-end statement as a PDF, or scan paper ones: in the Files app, tap the More button, tap Scan Documents and hold each page in view of the camera, then choose a location and tap Save. Use one folder per account, with a "Basis" folder inside for purchase records. The IRS says the requirements for paper records also apply to electronic storage, so PDFs are fine.

The less manual way. Paperlock reads each statement as you save it, picks out who it's from, the date and the amounts, and files it behind Face ID with no folders to name. When you finally sell, "what did I pay for the index fund in 2018?" comes back with the confirmation attached, or an honest "not in your vault" if it isn't there.

Keep the proof of cost until the sale's review window closes, keep the tax forms with their returns, and let the monthly statements go.