Read enough retail credit ads and you'll see both phrases used as if they mean the same thing. Most of the time they do. When they don't, the difference costs you money. Here's the quick guide.

Definitions

'0% APR' is a regulated statement under the FCA's CONC rules — it means the Annual Percentage Rate of Charge is zero, including any mandatory fees. 'Interest-free' is a marketing term with no legal definition; it means interest isn't charged, but fees might be.

The activation-fee model

The classic gotcha: a £200 sofa on '24 months interest-free' with a £29 'account activation fee'. No interest is charged, so the ad is technically accurate — but the effective APR once you include the fee is 12%, not 0%. Always look for the APR line, which is legally required to appear in the same box as 'interest-free'.

The score is a mirror, not a verdict. Lenders look through it, not at it.

When 0% isn't really 0%

0% deferred-interest deals (common on furniture and electronics) charge you 39.9% backdated from day one if you miss the final payment window by even a day. That's not the same as a genuine 0% APR product like a credit card intro offer, where the worst case is you fall to the standard rate on the remaining balance only, going forward.

Regulated vs unregulated credit

Any consumer credit under £25,000 for personal use is regulated by the FCA. That means the APR box, the pre-contract disclosure, and the 14-day cooling-off right all apply. If a lender tells you an offer is 'unregulated' to skip disclosures, walk away — it's either a scam or a business loan being missold.

Buyer checklist

Before you sign anything with '0%' in the headline: (1) find the APR box, (2) find the total repayable figure, (3) check whether interest is deferred or not, (4) note the final payment date and add a diary reminder two weeks before. Four checks, sixty seconds, no surprises.

The bottom line

Credit is a long game. Small, consistent moves — on-time payments, low utilisation, and honest paperwork — beat any single silver-bullet product. If you take one thing from this guide, take that.