Capital Gains Tracking: How to Prepare for Tax Season

Short-Term Capital Gain: Profit from selling an asset held 12 months or less. Taxed at ordinary income rates — up to 37% federal for high earners. RSU shares sold within 12 months of vesting, and stock options exercised and sold quickly, typically generate short-term gains.

Long-Term Capital Gain: Profit from selling an asset held more than 12 months. Taxed at preferential rates: 0%, 15%, or 20% depending on income. High earners (above ~$518,000 for single filers in 2026) pay 20% plus 3.8% NIIT, for an effective rate of 23.8%. Holding an appreciated position for 12 months converts a high-rate gain to a lower-rate gain.

Form 1099-B: The tax form issued by brokerages reporting proceeds from securities sales. Shows each sale transaction, proceeds, cost basis (if the brokerage tracked it), and whether the sale was short-term or long-term. You receive one 1099-B per brokerage per year. Multiple brokerages mean multiple 1099-Bs.

Schedule D: The IRS form where capital gains and losses are reported. Summary of all transactions from your 1099-Bs, plus any carryover losses from prior years. Schedule D calculates your net capital gain or loss and feeds into your Form 1040.

Why April Is the Wrong Time to Think About Capital Gains

The 1099-B lands in your email in January or February, and you open it to find you owe $40,000 in capital gains taxes you didn’t fully budget for. This is a common scenario for high earners with equity comp, and it’s largely preventable.

The problem is timing. Most people think about capital gains when tax season arrives. Effective capital gains planning happens throughout the year:

Before you sell appreciated positions (decide whether to wait for long-term treatment)
When you harvest losses (to offset gains you’ve already realized)
When RSU vests create ordinary income that affects your marginal rate (and therefore the benefit of a Roth conversion, charitable gift, or other rate-sensitive decision)

Short-Term vs. Long-Term: The 12-Month Rule

The single most impactful capital gains decision for most investors: whether a gain is short-term or long-term.

For a high earner facing a 23.8% long-term rate vs. a 37% short-term rate: the difference on a $200,000 gain is $26,400. Waiting one extra day past 12 months from purchase saves more than many people earn in a month.

This math applies to every appreciated position in your portfolio. Before selling any significant holding, check: when was it purchased? If you’re within weeks of the 12-month mark, waiting is often rational.

For RSU shares specifically: the clock starts at the vest date, not the grant date. Each vest creates a new lot. A lot that vested in March 2025 becomes long-term in March 2026.

How Multiple Brokerages Complicate Tracking

Capital gains are tracked per brokerage, per account. Your 1099-B from Schwab covers your Schwab account. Your 1099-B from E*Trade covers your equity comp account. Your 401(k) generates no capital gains 1099-B (tax-deferred account).

If you have taxable positions at three brokerages, you have three separate gain/loss positions. Tax-loss harvesting works across brokerages — losses at Schwab can offset gains at E*Trade on your Schedule D. But you need to know what you have at each to plan effectively.

Mid-year, if you want to estimate your year-end capital gains liability, you need to:

Pull your realized gains/losses YTD from each taxable brokerage account
Estimate what additional sales you’ll make (RSU vests you plan to sell, rebalancing trades)
Calculate your estimated net capital gain position
Determine whether you have unrealized losses available to harvest to offset gains

A wealth aggregator shows your unrealized gain/loss position across connected accounts, which is the key input for harvesting planning. For realized gains (already sold), you need the transaction history from each brokerage.

Preparing for Schedule D

By February, you should have received 1099-Bs from every brokerage where you had taxable sales. Before filing:

Collect all 1099-Bs
Import them into your tax software or provide to your CPA
Review the cost basis — brokerages don’t always have accurate basis for older lots, lots transferred between brokerages, or RSU shares (where the basis is the vest-date income you already paid tax on)
Apply any carryover losses from prior years
Calculate net short-term and long-term capital gain

The most common error is double-paying tax on RSU income. The vest value was already income on your W-2. The cost basis for those shares is the vest-date price. If your 1099-B shows a cost basis of zero (common for equity comp shares reported on a transfer), you need to correct it — otherwise you’ll pay tax on the full sale proceeds when you already paid tax on the vest value.

Q&A

What's the tax rate difference between short-term and long-term capital gains for high earners?

For a single filer with taxable income above $518,900 in 2026: short-term gains are taxed at 37% (ordinary income rate). Long-term gains are taxed at 20% plus 3.8% NIIT = 23.8%. The difference is 13.2 percentage points. On a $100,000 gain, holding one extra day past 12 months saves approximately $13,200 in taxes. This math makes the 12-month holding period threshold critical for tax planning.

Q&A

How do I track capital gains across multiple brokerages?

Each brokerage tracks its own transactions and provides a 1099-B in January/February for the prior year. For proactive tracking during the year, you need either a consolidated view across brokerages (which wealth aggregators provide for connected accounts) or a separate tax tracking tool (like TurboTax's portfolio tracking or a spreadsheet). Many people only discover their capital gains position in February when the 1099-Bs arrive — too late to take any action.

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Do I have to pay capital gains tax on unrealized gains?

No. Capital gains tax is triggered only when you sell an asset at a profit. Unrealized gains — paper profits on holdings you still own — create no tax liability until you sell. However, understanding your unrealized gain position is important for planning: large unrealized gains mean a large potential future tax liability when you eventually sell.

How do RSU sales affect my capital gains tracking?

RSU shares vest as ordinary income — the vest value appears on your W-2. After vesting, the cost basis for each lot equals the vest-date fair market value. Any appreciation or depreciation after vesting is a capital gain or loss. Selling within 12 months of vest = short-term capital gain/loss. Selling 12+ months after vest = long-term capital gain/loss.

What is carryover loss and how do I use it?

If your capital losses exceed your capital gains plus $3,000 in a tax year, the excess carries forward indefinitely to future years. Carryover losses offset future capital gains dollar-for-dollar. A year with significant tax-loss harvesting might generate losses that reduce your tax bill for 5+ subsequent years. Your carryover loss balance appears on Schedule D from your prior year's return.

Should I wait until December to do tax-loss harvesting?

No — harvest losses year-round when positions are at a loss. Waiting until December means missing opportunities created by market volatility earlier in the year. Many investors harvest in the spring after Q1 market volatility, after RSU vesting events, and in December as a year-end clean-up. The wash sale rule applies regardless of timing.

How do I get a consolidated view of my capital gains across all accounts?

Wealth aggregators that connect to your brokerage accounts show your holdings and unrealized gains across all accounts. For realized gains (already sold), you need your brokerage's transaction history. For a complete picture mid-year, you may need to pull realized gain summaries from each brokerage manually — or use a tax planning tool that tracks transactions.

Keep reading

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