Brokerage Account Calculator

Before you enter your numbers

Enter the expected gross return, expense ratio and annual tax drag as percentages of account value. Tax drag is a percentage-point reduction in return. It is not your marginal tax bracket: entering 24 because your bracket is 24% would model a 24-percentage-point annual drag.

• Current account balance
• Monthly contribution
• Years
• Expected annual return

Input reference

• Current balance: The current balance committed to this goal. Use a recent statement and exclude money reserved for unrelated goals. This starting value is already invested, so do not also enter it as a recurring contribution.
• Monthly contribution: New money added at the end of each month. Convert annual saving to a monthly amount by dividing by 12. This page does not schedule skipped months or one-time deposits automatically.
• Years: The duration of the calculation in years. Longer periods give growth or withdrawals more time to operate. This is a chosen modeling horizon, not a prediction of an investment term or your lifetime.
• Gross annual return: An assumed nominal annual rate, divided by 12 in monthly projections. It is held constant. It is not a guaranteed yield, and the default should be replaced with an assumption suited to your scenario.
• Account fees: An annual percentage-point deduction from the gross return assumption. Check whether the source return already deducts this fee. One-time charges, trading costs and fixed account fees are not modeled by this field.

Formula and calculation method

Net annual planning return = gross return − expense ratio − tax drag. The model applies that rate monthly to the balance and contributions. It does not track individual tax lots, cost basis, realized gains or unused losses.

Worked example

With a 7% gross return, 0.5% fees and 1% annual tax drag, the planning rate is 5.5%. A tax drag of zero leaves a 6.5% rate under the same fee assumption. Compare the resulting balances using identical contributions and holding periods.

How to interpret the result

The result panel reports projected account value, total contributions and estimated growth.

Dividend taxes, interest taxes and capital-gains taxes arrive at different times and can depend on your jurisdiction. Tax due on an eventual sale may not be fully represented by a flat annual drag. Tax-loss harvesting, turnover and account location can change outcomes but are not simulated.

Why taxable accounts need a tax-drag assumption

A taxable brokerage account can lose part of its gross return to taxes on dividends, interest and realized gains. The calculator lets you enter an estimated annual tax drag and subtracts it, together with account or fund fees, from the gross return before compounding.

Tax drag is only a planning shortcut. Actual tax depends on the assets held, turnover, distribution types, holding periods, losses, jurisdiction and the investor’s tax situation.

Separate annual drag from final-sale tax

Annual tax drag summarizes money lost to recurring taxes as a percentage of account value. A final sale can realize gains accumulated for years. Applying a flat annual drag does not establish that the ending balance is fully after tax, particularly when turnover has been low.

Account costs can also be fixed currency charges rather than a percentage. A fixed fee consumes a larger fraction of a small balance. This page only provides a percentage expense field; reduce planned contributions for predictable fixed charges or use a separate cash-flow model if precision matters.

Treat tax drag as an approximation, not a tax return

Taxable accounts can lose part of their gross return to dividend taxes, interest taxes, realized capital gains and fund distributions. The calculator models tax drag as a simple annual percentage reduction, which is useful for scenarios but cannot reproduce the timing and character of every taxable event.

Use a smaller tax-drag assumption for tax-efficient holdings and a larger one only when it is justified by the investment and your tax situation. Keep account fees separate so you can see how both costs reduce projected growth.

Use The Result In The Next Calculation

Use the brokerage projection when taxable-account fees and a simplified tax drag matter. If taxes are not part of the question, compare the same deposits with the investment calculator to isolate the effect of the drag assumption.