Tax Extensions for People With Complicated Investment Income
Form 1099-DA reached crypto investors for the first time in early 2026, covering sales made during 2025. It reports what each asset sold for and stops there, since brokers carried no basis-reporting obligation in that first round. Reconstructing what every lot originally cost falls to the holder. That is one form, in one asset class, for someone whose portfolio may also hold partnership interests and a brokerage account that revises its own statements in March.
The Paperwork Timeline for Investors
An investor’s documents arrive in waves, and the last wave comes after the April deadline. Consolidated brokerage statements were not due to recipients until February 17 in 2026, already later than the January 31 date that governs most other information returns.
Then the revisions begin. A brokerage that reclassifies a dividend or adjusts basis after a corporate action issues a replacement statement, and those replacements appear through the spring. Partnership interests are slower still, since an entity that extends its own return has until September 15 to send the K-1 the investor needs.
The document calendar and the April 15 deadline were set independently, and they do not line up. Anyone holding more than a portfolio of index funds is being asked to file a return before the numbers that determine it have stopped moving.
Wash Sales Across Multiple Accounts
The wash sale rule disallows a loss when substantially identical securities are repurchased inside a 61-day window, counting the sale date, the 30 days before it, and the 30 days after. The disallowed amount is added to the basis of the replacement position, so the deduction is deferred rather than destroyed.
Brokers handle this within a single account. They calculate the disallowed loss and roll it into the replacement basis, flagging the transaction on Form 1099-B. What they do not do is look anywhere else.
No broker tracks wash sales across two brokerages, between a taxable account and an IRA, or between spouses filing jointly. Sell at a loss at one firm and repurchase at another, and the two statements that arrive show nothing wrong. The adjustment has to be entered by hand on Form 8949 with code W. A repurchase inside an IRA is worse than a deferral. The loss is disallowed permanently, with no basis adjustment anywhere to recover it.
Finding these takes a full reconciliation across every account, which is the kind of work that does not compress into the first two weeks of April.
The exposure grows with trading activity. Harvesting losses in December and rebalancing in January creates the exact conditions the rule targets, often without any intent behind it, and the 61-day window spans the year end in a way that puts both sides of the problem in different tax years.
Submitting the Request Early
The request itself takes minutes. What it needs is a good-faith figure for the year’s total liability and nothing at all from the statements still in transit, which is why an investor can submit a FileTax online tax extension in early April with a portfolio that is still unreconciled.
What the form does require is a payment. The estimate drives the number, and the number has to meet one of the safe harbor thresholds to keep the penalty off.
Crypto Reporting in Transition
The reporting rules for crypto are phasing in across three filing years, and each year behaves differently. The IRS finalized the crypto reporting regulations in 2024, and the phase-in schedule they set is the reason.
For 2025 transactions, brokers reported gross proceeds only. The forms issued in early 2026 show what an asset sold for and say nothing about what it cost. For 2026 transactions, brokers report both proceeds and basis, but only for covered assets, meaning those acquired on or after January 1, 2026 and held continuously at the same broker since. Anything bought earlier, or moved between wallets and platforms, falls outside that definition and stays the holder’s responsibility.
The practical result is that a crypto investor filing for 2025 or 2026 is working from personal records for most positions. Reconstructing basis across several years of exchange activity, including transfers that no single platform witnessed end to end, is not a two-week project.
None of this is settled. The agency’s cryptocurrency guidance has been revised repeatedly since the first version landed, and the obligations attached to decentralized platforms remain in litigation. The benefit of a rule that changed mid-year goes to whoever files in October with the final version in hand.
The Safe Harbor for Estimated Payments
More than half of US households hold some investment in the stock market, and for the portion of them holding assets outside a retirement account the income is volatile, which makes the current-year liability hard to predict and makes the prior-year benchmark useful. A taxpayer who pays in 90% of the current year’s tax, or 100% of the prior year’s tax, avoids the underpayment penalty. For anyone whose prior-year adjusted gross income exceeded $150,000, the second figure rises to 110%, and it falls to $75,000 for married taxpayers filing separately.
This is the most reliable tool available to someone extending with unfinished numbers. The prior-year figure is known exactly. An investor who remits 110% of last year’s tax by April 15 is protected from the underpayment penalty no matter how the current year turns out.
The protection has a boundary. Satisfying the safe harbor prevents the penalty, and it does nothing about the balance itself. A year with large realized gains still produces a bill in October, and interest runs on any amount that was not paid in April.
The Amended-Return Alternative
The alternative to extending is filing in April on incomplete data and correcting it later. That path has costs the first path does not.
An amended return on Form 1040-X is processed as a lower priority than current-year filings, which means a correction can remain open long after it was sent. It also produces a second version of the same year for the IRS to reconcile, and for an investor whose corrections arrive in waves, one amendment often turns into two.
Extending produces a single return, prepared once, incorporating every correction that arrived between February and September. For a portfolio generating corrected statements, that is a lower error rate and less work overall.
The comparison is not close for anyone holding partnership interests. A K-1 that arrives on September 20 cannot be reflected in an April filing under any approach, so the choice there is between extending and amending a return that was known to be incomplete when it was signed.
The Stakes of an April Guess
An investor who files early on unreconciled numbers is exposed in two directions. Underreport a gain and the return is wrong in the direction the IRS cares about most, with a 6-year assessment window attached to any omission above 25% of gross income, and the agency has spent years probing major crypto brokers and other intermediaries for exactly that kind of gap. Overreport it and the overpayment stays with the Treasury until an amendment recovers it, assuming the error is ever caught.
The extension removes that exposure for the price of a form and an accurate April payment. Skipping it leaves a return built on numbers that were still moving when it was signed.
