Tax errors can be costly for small businesses. Accidentally failing to comply with tax laws, violating tax codes, or filling out forms incorrectly can leave taxpayers and their businesses open to possible interest and penalties. The IRS has stated that the most common errors by small businesses include underpaying estimated taxes and depositing employment taxes late or incorrectly. Other common mistakes are not separating business and personal expenses, which could trigger additional scrutiny from the IRS, and filing late returns. Using a tax advisor is one way to avoid these kinds of errors, the tax agency noted.