Every concept, endless questions
Each concept is a small financial model. Read how it works, then draw a real interview question from it: forwards, backwards or what-if, with fresh numbers and a worked solution every time.
Forward runs a concept the usual way. Inverse runs it backwards, which is what separates understanding from memorizing.
Tax & Fees
4 conceptsFee drag compounded
A 1% fee sounds like 1% of the money. It is actually 1% of the money every year, and each year’s fee also removes the growth that money would have earned for every year after. Over thirty years that compounds into a quarter of the client’s ending wealth — and a far larger share of the investment gain, because the fee is charged on the capital as well as the return. That is why the fee is the most reliable predictor of net returns an adviser has: markets are uncertain, costs are not. The same arithmetic tells you how much an active manager must beat the market by, every single year, just to stand still against an index fund.
Tax-loss harvesting
When an investment is below what the client paid for it, selling turns a paper loss into a tax deduction without changing their market exposure — they buy something similar with the proceeds and stay invested. The deduction is not free money: the replacement now has a lower cost basis, so the loss comes back as a bigger gain when it is finally sold. What harvesting really buys is time. Tax is paid later instead of now, the saved tax compounds in the meantime, and if the client’s rate is lower later — or the position is never sold — the deferral becomes a permanent saving. The traps are the wash-sale rule and forgetting that losses offset gains before ordinary income.
Taxable-equivalent yield
A municipal bond yielding 3.5% can beat a corporate bond yielding 5%, because the investor keeps all of the first and only part of the second. The taxable-equivalent yield puts them on the same footing: the taxable yield the client would need to end up with the muni’s income after tax. It rises with the tax rate, which is why munis are a high-bracket product — and why holding them inside an IRA, where the tax break is wasted, is a classic mistake. The break-even tax rate turns the comparison into a single question: is this client’s marginal rate above or below it?
Roth versus traditional
A traditional account takes the tax break now and pays tax on the way out; a Roth pays the tax now and lets everything out tax-free. Multiplication does not care about order, so if the tax rate is the same at both ends the two produce exactly the same after-tax money — the growth is sheltered either way. The whole decision is therefore a bet on one number: is the client’s tax rate higher today or in retirement? The one wrinkle is contribution limits. A dollar in a Roth is worth more than a dollar in a traditional account, so when the client can only put in a fixed amount, the Roth shelters more money.