Grammar fix

run up

to allow a bill or debt to increase

To spend money or use services so that you owe a large amount, often without noticing how much it adds up.

phrasal verbB2common

Hear it in context

Notice where the phrase sounds natural.

He ran up a huge phone bill calling his friends overseas.money
In my opinion, it's easy for students to run up debts if they don't keep track of their spending.IELTS speaking

Pattern: run up (something)

WrongShe ran up of a big bill.

RightShe ran up a big bill.

'Run up' takes the object directly — no 'of'.

Patternrun up (something)

Choose the version that sounds natural in speech.

Stiff He incurred a considerable debt on his credit card.

Natural He ran up a huge bill on his card.

'Run up' is the everyday verb for letting a bill grow; 'incur a debt' is formal/financial.

Words that usually travel with it.

Not the same as 'pay off', which means to finish paying a debt.