Onsite deputation and client travel: forex cards for engineers going abroad

Published: 21 October 2026

Category: how-to-guides | cardbuzz

Tags: credit cards, it professionals, forex, international travel, onsite, travel rewards

The onsite stint is a rite of passage in Indian IT — three months at the client site, or a year on deputation, or the endless short trips of a consulting role. It is also a financial regime change: your spending moves to a foreign currency, your Indian cards suddenly carry forex markups, and the company hands you a per-diem or a corporate card with rules of its own. Engineers who plan the card side of onsite travel keep thousands; those who wing it pay a quiet tax on every transaction abroad.

This guide covers how international card mechanics work, when a forex-focused card earns its place, how to handle the company's money alongside your own, and how to bring the rewards home.

What changes when you swipe abroad

Three mechanics activate the moment your card leaves India.

First, the forex markup. International transactions convert at the network rate plus the issuer's markup — a percentage on every swipe, every ATM withdrawal, every online purchase in foreign currency. On months of onsite living expenses, this is not a rounding error; it is one of the largest avoidable costs of working abroad.

Second, dynamic currency conversion. Overseas merchants often offer to charge you in rupees "for convenience". Decline it, always. The merchant's conversion rate is worse than your card network's rate plus markup in virtually every case. Pay in the local currency and let the card handle conversion.

Third, reward treatment. International spends usually post as international transactions, and programme terms vary on whether they earn accelerated or base rewards. Some programmes exclude international transactions from category acceleration entirely; others treat them normally. Check the terms of the cards you carry before assuming your dining or shopping acceleration applies abroad.

Forex cards versus credit cards: the real comparison

The classic onsite question is whether to load a prepaid forex card or just use a credit card. The honest answer: they solve different problems.

A prepaid forex card locks in the exchange rate at load time and typically carries lower conversion costs than a standard credit card's markup. For budgeting a fixed per-diem or a known set of expenses, rate-locking removes uncertainty. The trade-offs: loading and reloading takes planning, acceptance is narrower than the major card networks, and prepaid cards earn no rewards.

A credit card with low or zero forex markup gives you network acceptance everywhere, rewards on the spend, and no pre-loading logistics. For engineers whose onsite expenses are large — rent deposits, furnishing a temporary flat, months of living costs — the rewards on that volume can be substantial. The trade-off is rate uncertainty: you get the rate on the posting date, not the date you planned.

Many experienced onsite travellers use both: the forex card for budgeted, fixed expenses where rate certainty matters, and the low-markup credit card for variable spend where rewards and acceptance matter more.

Which card archetype suits onsite life

A travel card with low forex markup is the natural primary card abroad. It is built for exactly this: international acceptance, travel-category acceleration on flights and hotels, and lounge access that matters disproportionately during months of airport transits. If you hold one, the onsite stint is its highest-value deployment.

A general rewards card with low forex markup is the fallback — the international spend earns its standard rate, which on high onsite volumes is still meaningful. What matters more than the archetype is the markup term: a high-markup card of any archetype is the wrong card abroad, full stop.

What to avoid: carrying only a domestic-optimised card with a standard markup and discovering the cost three months in. Check the markup before you fly, not after the first statement.

Company money: per-diems, corporate cards and reimbursements

Onsite finances usually involve the employer's money, and the mechanics matter.

If you receive a corporate card, learn its rules before the first swipe: what categories are allowed, what documentation is needed, and whether personal use is permitted or prohibited. Corporate cards typically earn no personal rewards — the points accrue to the company — so there is no optimisation to do beyond compliance. Keep personal and corporate spends strictly separate; mixing them creates reimbursement disputes.

If you receive a per-diem or are reimbursed against bills, the card strategy flips in your favour: pay everything on your personal low-markup card, collect the rewards on the full volume, and let the per-diem or reimbursement clear the balance. This is the single highest-reward situation most engineers ever encounter — months of living expenses routed through a personal card. Two disciplines: file expense claims promptly so reimbursements land before the card's due date, and never spend the per-diem float on anything but the card bill until it clears.

Practical onsite card hygiene

A few operational habits save real pain. Inform your issuer of travel dates so international transactions do not trigger fraud blocks — a blocked card in a foreign supermarket is miserable. Carry two cards from different networks; if one network has an outage or a merchant does not accept it, you have a fallback. Keep the Indian auto-debits (subscriptions, EMIs, insurance) running on a card you leave active at home — onsite life is not the time to discover your home loan EMI bounced. And download the issuer's app with international roaming or app-based authentication sorted before departure; OTP delivery to an Indian number abroad is a classic failure point.

Bringing it home: rewards and tax awareness

Rewards earned on onsite spend are real value — redeem them against travel, which you will have plenty of, or per the programme's best-value options. One caution: large foreign-currency card activity can attract attention in tax filings; keep records of what was personal versus reimbursed, and consult a tax professional on how per-diems and allowances are treated. The rewards are yours to keep; the documentation is yours to maintain.

Key takeaways

  • Always pay in local currency abroad and decline dynamic currency conversion at the terminal.
  • Compare a prepaid forex card (rate certainty, no rewards) against a low-markup credit card (acceptance plus rewards) and consider using both.
  • Make a low-forex-markup travel or rewards card your primary card for the onsite stint; check markup terms before flying.
  • Keep corporate and personal spends strictly separate; on per-diem models, route everything through your personal card and let reimbursements clear the balance.
  • Notify issuers of travel dates, carry two networks, and keep Indian auto-debits running on a home card.
  • Sort app-based authentication before departure — OTPs to Indian numbers abroad fail at the worst moments.
  • Keep clean records of personal versus reimbursed spend for tax filing.