A more thorough explanation:

A write-off is when an asset is removed from the books, usually as a loss or expense. This is different from deducting an item, which means subtracting it from gross income or adjusted gross income when calculating taxable income.

In personal injury cases, a write-off refers to the difference between the original amount of a medical bill and the amount accepted by the medical provider as full payment. For example, if a medical bill was originally $1,000 but the medical provider accepted $500 as full payment, the write-off would be $500.

Write-offs can be important in determining the reasonable value of medical care in personal injury cases. In the past, there was confusion over whether evidence of write-offs could be excluded under the collateral-source rule, which prevents the jury from learning about a plaintiff's income from a source other than the tortfeasor. However, courts have generally allowed evidence of write-offs to be admitted because they are not considered payments or benefits to the plaintiff.

For example, if a plaintiff in a personal injury case incurred $10,000 in medical expenses but the medical provider accepted $5,000 as full payment, the write-off would be $5,000. The plaintiff would be entitled to recover the reasonable value of the medical care, which could be determined by considering the original amount of the medical bill, the amount accepted as full payment, and any other relevant factors.