Every expense platform runs on a card, and the kind of card decides when money leaves the business account, whether interest is possible, who is liable, and who holds the money in the meantime. This guide explains the four types, then the rules, fees and protections that follow from each.
The four types
| Type | Where the money comes from | Repayment | Interest | Credit check |
|---|---|---|---|---|
| Charge card | Credit, settled each cycle | In full every period | None if paid on time | Yes |
| Credit card | A revolving credit line | Minimum or in full | On any carried balance | Yes |
| Debit card | The business account balance | None, spends directly | None | Usually no |
| Prepaid card | A balance loaded in advance | None | None | Usually no |
The software on top, receipt capture, approvals and accounting sync, looks similar across platforms. The card type underneath is what changes the cash flow and the risk.
Charge cards: the US default
Most US expense platforms issue charge cards. Mercury's IO page says customers must "pay off your full IO balance every pay period", with new customers on daily repayment until balances reach $15,000. Ramp's pricing page describes a "corporate liability charge card".
How a cycle works. Spending builds up through the period, then the whole balance is collected from the linked business account on the due date. If the team spends $18,000 in a 30-day cycle, $18,000 leaves the account on the due date. There is no interest because no balance is carried.
How limits are set. Rather than a fixed credit line, charge card limits are often set from the business's cash balance and cash flow, and can rise or fall as those change. A business with a falling balance can see its limit fall too.
What it suits. Businesses with steady cash that want card spending in one place without paying interest.
Credit cards: carrying a balance
A business credit card works like a personal one: there is a credit line, a minimum payment, and interest on any balance not paid in full. Few US expense platforms lead with revolving credit; it is more common on cards from banks and card issuers, and some UK platforms, such as Payhawk, mention credit cards alongside debit cards.
What carrying a balance costs. US card issuers usually turn the APR into a daily rate by dividing it by 360 or 365, then apply it to the balance at the end of each day (CFPB). On $10,000 carried for 30 days at an illustrative 24% APR, that is about $197 of interest. Our guide to APY, AER and APR explains the arithmetic.
Debit cards: spending what is there
A debit card spends directly from the business account, so the limit is the balance and there is nothing to repay. This is common in the UK, where many platforms issue debit cards against money the business has moved onto the platform. There is no credit decision, which makes debit cards easier to get for new businesses.
Prepaid cards: budgets loaded in advance
A prepaid card spends a balance loaded onto it in advance. Expense platforms use this to give each employee or team its own budget: a card loaded with £500 for a trip cannot spend £600. When the card is empty, spending stops until it is topped up, so the budget is enforced by the card rather than by an approval rule.
Business cards and consumer protections
In the US, Regulation Z is the rule behind most consumer credit card protections, and it lists "an extension of credit primarily for a business, commercial or agricultural purpose" among the transactions it does not cover (12 CFR 1026.3). Business card terms therefore come mainly from the card agreement. Repayment terms, liability for misuse, fee changes and what happens after a missed payment are set there, so the agreement is the document to read before signing.
Who holds the money
US. Charge and credit cards are issued by banks, and the platform is the technology layer. Mercury IO is issued by Patriot Bank; Ramp's cards are issued by banks including Celtic Bank; Rho names Lead Bank and Webster Bank.
UK. Money loaded to expense cards is usually electronic money. The Electronic Money Regulations 2011 define it as stored monetary value "represented by a claim on the electronic money issuer" (legislation.gov.uk). An e-money institution "must safeguard" customer funds, either by keeping them segregated in a separate account at an authorised bank or the Bank of England, or by covering them with insurance or a comparable guarantee (regulation 20).
Safeguarding is not deposit protection. The FSCS does not cover e-money, as Mettle's fee document puts it for e-money institutions generally. Pleo's UK cards, for example, are issued by Pleo Financial Services UK Ltd, an e-money institution. Our guide to FDIC and FSCS protection explains the difference in detail.
Who is liable: the company or the employee
On a corporate-liability card, the company owes the balance, not the employee holding the card. Ramp's description of its card as "corporate liability" means exactly that. Employees submit receipts so the business can account for spending, and the expense policy covers what happens with personal or unapproved spending.
Fees that follow the card type
Foreign exchange. For teams that spend abroad, FX fees often matter more than the subscription.
| Platform | Market | FX fee (read 29 Oct 2026) |
|---|---|---|
| Rho | US | 1% |
| Payhawk | UK | Mid-market rate plus 0.3% |
| Pleo | UK | 2.00% (Start), 1.75% (Build), 1.49% (Optimise) |
| Mercury IO | US | International fee charged; rate not published on the page read |
On £5,000 of foreign spending a month, Pleo's Start plan charges about £100, its Optimise plan about £74.50, and Payhawk's 0.3% margin about £15.
Cash withdrawals. Pleo charges £5 per ATM withdrawal on Start and nothing on Build and Optimise.
Interest. Only on credit cards with a carried balance.
Cashback, and who pays for it
Card rewards are paid for largely by the fees merchants pay on each transaction, which is why they appear on charge and credit cards more than on debit and prepaid ones. Mercury IO publishes 1.5% cashback on all spend: $15,000 a month earns about $225. Rho mentions up to 2% under its Platinum terms, and Spendesk mentions cashback from 1% for eligible clients. A platform with cashback but a higher FX fee can still cost more for a team that spends abroad.
Questions to answer before choosing
- Does the business have steady cash to clear a charge card in full each cycle?
- Does it need to carry a balance, and at what APR?
- How much is spent in foreign currencies each month?
- Does each employee or team need a hard budget (prepaid) or a limit set centrally?
- Is the money held at a bank, or as e-money that is safeguarded but not FSCS-protected?
- What does the card agreement say about liability and missed payments?
Comparing platforms
Our US expense card comparison and UK comparison rank platforms on published costs. The expense card cost calculator lets you set team size, spend and foreign share.
Recap
- A charge card is paid in full each period, so no interest builds up, but the business needs the cash on the due date.
- A credit card allows a carried balance, and interest is charged on it daily.
- Debit and prepaid cards spend money already held, so the limit is the balance and there is nothing to repay.
- In the US, most consumer card rules do not cover credit extended for a business purpose; the card agreement sets the terms.
- UK expense cards are usually e-money: safeguarded by law, but not covered by the FSCS.
- Foreign-exchange fees differ more between platforms than subscription prices do for teams that spend abroad.
Sources
Read on or before 4 November 2026. Rates and rules change; the source page is the current version.
- Mercury's IO page mercury.com
- Ramp's pricing page ramp.com
- Payhawk payhawk.com
- CFPB consumerfinance.gov
- 12 CFR 1026.3 consumerfinance.gov
- legislation.gov.uk legislation.gov.uk
- regulation 20 legislation.gov.uk
- Mettle's fee document mettle.co.uk