Accrue and incur often appear in discussions about money. Both can describe costs, but they focus on different things: amounts building up and someone becoming responsible for them.
Accrue usually means to build up over time. Interest, savings, benefits, and expenses can all accrue. The word does not mean that something is always positive: interest can build up in a savings account or on an unpaid debt.
- Your savings accrue interest each month.
- Interest continued to accrue on the unpaid balance.
You can put the growing amount first, as in Interest accrues, or name the person or thing collecting it, as in The account accrues interest.
Incur means to become responsible for a cost or to experience something unwanted, such as a loss or penalty. It focuses on the expense or consequence you take on, not on how gradually it grows.
- We incurred extra costs when we changed our travel dates.
- The company incurred a loss on the sale.
The same expense can be described from both angles. Storage charges may accrue while your belongings remain in a warehouse. You incur those charges by using the storage service.
This is not a strict contrast between slow and sudden events. You can incur expenses repeatedly over several months. Choose the verb according to whether you mean accumulation or taking on a cost or unwanted consequence.