An offer letter is written in the employer's interest: one big number, a currency symbol, and a start date. The number that decides whether you are better off is smaller, arrives later, and is quoted in a different currency.

1. The take-home percentage

Ask payroll, in writing, what percentage of gross reaches your account after income tax, social insurance, pension contributions and any local levies. Across developed economies the tax wedge on an average salary commonly runs between roughly 20% and 45% of employer cost, so the same gross figure can mean very different monthly money. The OECD's Taxing Wages series publishes the comparison by country and family type if you want a reference point.

A 10-percentage-point difference in take-home on a salary of 50 million won a year is 5 million won — larger than most relocation allowances.

2. Housing, at the price you would actually pay

"Accommodation provided" is a benefit worth its market rent, not its description. If the flat is a 40-minute commute from the office and you would have rented closer, you are being paid in inconvenience. Get the address, look up the rent, subtract it from the package. If the employer pays a housing allowance instead, check whether it survives the first year and whether it is taxed.

3. The cost of sending money home

This is the number that quietly decides how the job feels. If you plan to remit 10% of your salary monthly, a 1% all-in route versus a 4% route is a 3% difference on that slice every month — and it compounds into years. Compare full quotes: transfer fee plus the exchange rate actually applied, not the advertised "zero fee".

4. The currency you earn versus the currency you spend

A salary paid in a strong currency and spent in a weak one is a raise; the reverse is a trap. Write both currencies down, and note which side your fixed costs are on — a mortgage or student loan back home, family support, insurance. Those costs do not move when your salary's currency moves.

5. The price level for your basket

Cost-of-living indices compare an average basket that belongs to no one. Build your own: rent, commute, groceries, childcare, the mobile plan, the gym, the occasional flight home. Ten lines are enough. A city can be 30% cheaper on the index and more expensive for a family of four that needs a three-bedroom near a school.

6. The cost of leaving

Pension and severance rules can be worth several months of salary — or nothing, depending on how long you stay and which visa you hold. Ask what happens to employer pension contributions if you leave after two years, whether severance accrues from day one, and who pays the flight home. An offer that is 15% better on salary but forfeits a 10% pension entitlement is a smaller raise than it looks.

Putting the six together

Assume an offer of ¥6,000,000 a year in Japan against a current ₩62,000,000 in Korea. The headline comparison depends entirely on the exchange rate you use, so fix one realistic rate and keep it: at 100 yen to 900 won, the offer is ₩54,000,000 — nominally less. Then adjust: if take-home is 78% there against 82% here, monthly net is ¥390,000 against ₩4,236,667, or about ₩3,510,000 against ₩4,236,667 at the same rate. Housing and commuting then decide whether the gap is real; the price level decides whether it matters.

These are illustrative figures, not forecasts. The point is the shape of the arithmetic: four of the six numbers can reverse the answer, and none of them appears in the first paragraph of an offer letter.

What to request before signing

  • A written net-pay projection for the first twelve months, including the first partial month.
  • The housing arrangement in writing: address, rent, who pays, what happens in year two.
  • The pension and severance rules, with the vesting period spelled out.
  • The relocation and repatriation terms, including flights for dependants.
  • The currency of payment, the payroll date, and who bears the conversion cost.