The process (and accounting practice) of increasing the recorded value of an asset or a liability. It also refers to the increase in that value.

In relation to assets, it is the increase in the book value of an asset that does not result from a cash payment or an addition of other assets or incurring a liability, or issuance of stock. In general, write-up is a legal practice in the area of accounting. However, some exceptions are there particularly in the cases involving fixed assets purchased under mergers (the so-called purchase method mergers).