§ 21707 Invoice Alteration Prohibition

• •You can't change or mess up a sales receipt or bill of sale.
• •It's against the law to alter any details on these documents.
• •This rule applies unless there's a special exception in another law.

You buy a used bike and get a bill of sale. Later, you change the price on the bill to show you paid less than you actually did.

This is illegal because you altered the bill of sale. You could get in trouble for doing this.