Credit line

The maximum amount your bank lets you charge on a card. It's based on your verifiable income, your record at Buró de Crédito (Mexico's credit bureau), and how you've used credit before. Asking for an increase within the first six months almost always gets rejected; after a year of good behaviour, banks raise it automatically.

Two flavors in Mexico. Revolving line (a card): you draw, pay, it frees up and you draw again, with interest only on what's used. Simple line (a personal loan): you get a lump sum and repay it in fixed installments; once paid, it closes.

An expensive mistake: using the revolving line as if it were a term loan. If you buy a 15,000-peso appliance on the card and pay it off in dribs with a revolving balance, the 68% CAT makes it far pricier than a personal loan at 40% for the same thing. The card shines on purchases you clear within the interest-free window; for amounts you'll spread out, a term loan almost always wins.