Same investment, ₩1.54M in tax versus ₩297K — what one account changed, and the 3-year price

Two people invested in the same products in the same year and earned exactly the same: ₩10M in interest and dividends, and a ₩3M loss on another product. When the tax was worked out, one owed ₩1.54M and the other ₩297K, five times less. What differed was the account. One bought in an ordinary brokerage account, the other in an ISA, the account nicknamed the 'do-everything account'. But the name carries some exaggeration. It is not a free perk. It is a contract that trades three years of your time for the benefits.

The ISA, the Individual Savings Account, is a tax-advantaged account created by Article 91-18 of the Restriction of Special Taxation Act, and its benefits and conditions are all written in the law as numbers. Four steps: the account's shape, the three devices that cut tax, the price (three years and the caps) and the exits after year three.

Step one: the shape. Anyone 19 or older can open one, or 15 and older with earned income in the prior year. The rule is one account per person across all financial institutions. It can hold deposits and savings, funds, derivative-linked securities and domestic listed shares, and that breadth earned the nickname. There are two types: low-income if the prior year brought only earned income with salary of ₩50M or less, or comprehensive income of ₩38M or less with salary not above ₩50M; general otherwise. The type sets the tax-free allowance: ₩4M for low-income, ₩2M for general. Eligibility is judged at opening and at extension, and the tax office verifies income and notifies the institution. And some people are shut out: anyone whose financial income exceeded ₩20M, making them subject to comprehensive taxation, even once in the 3 years before opening or extending gets no ISA tax benefit.

Step two, the anatomy of the hook. In an ordinary account, 15.4% is withheld on interest and dividends, and losses are not recognized. Earn ₩10M on one product and lose ₩3M on another, and the tax is on the full ₩10M earned: ₩1.54M. The ISA calculates in a different order. Device one, netting: as of the closing date, only the net profit (all gains minus all losses inside the account) counts. ₩7M. Device two, the tax-free allowance: for the low-income type, ₩4M of that carries zero tax. Device three: the remaining ₩3M is taxed not at 15.4% but at 9%, 9.9% with local tax. ₩297K.

Step three: the price. The first condition is time. The contract must run at least 3 years, and closing before then claws back the tax benefits you received; only unavoidable reasons such as death or emigration are exempt. There is a lesser-known rule, though: even within the 3 years you can withdraw up to the principal you paid in. What the law treats as early closure is withdrawing more than you contributed. The second condition is the cap: ₩20M a year, with unused room carrying to the next year up to ₩100M in total. Miss the ₩20M in year one and year two allows ₩40M. Third, the tax-free allowance is per contract, not per year. The low-income ₩4M is not ₩4M every year but ₩4M applied once to the net profit up to closing. This account settles once, at maturity, in one large calculation.

Step four: the exits. After 3 years, three paths open. First, close and settle: net profit minus the allowance, taxed at 9.9%, done. Second, extend: you can lengthen the term before maturity, with low-income status re-assessed on income at extension. Third, move the balance into a pension account: after 3 years, putting all or part of the balance into pension savings or an IRP counts as maturity, and 10% of the transferred amount, up to ₩3M, is added to that year's pension contributions eligible for the tax credit. That portion is recognized separately from the credit cap covered in the pension episode. So the account's life is not 3 years but a cycle.

An honest calculation. Three kinds of people benefit greatly: deposit and savings-focused investors, whose 15.4% on interest drops to zero or 9.9%; investors in dividend stocks, bonds and overseas index funds, whose dividends and distributions are all subject to netting and the allowance; and people close to the comprehensive financial-income threshold, for whom the separate-taxation effect can outweigh the rate gap, provided they have not crossed it even once in the 3 years before opening. Where the effect is limited: people chasing only capital gains on domestic listed shares. For minority shareholders those gains are mostly untaxed even in an ordinary account, so on gains alone the ISA adds little, though the dividend benefit and netting share losses against other gains remain. The single test is this: how much is the 15.4% currently attached to your financial income costing you per year?

Two things to do now. Check the tax attached to last year's interest and dividends. That 15.4% is the size of your reason to open one. If you open one, first check whether you qualify for the low-income type. At ₩50M of salary or less the allowance doubles. Product choice, fees and maturity settlement vary by institution and circumstance, so read the terms yourself when opening. The reality behind the 'do-everything' name is not magic but a contract that trades three years for three devices.