After-Tax Profit Margin

What Does After-Tax Profit Margin Mean?
A financial performance ratio, calculated by dividing net income after taxes by net sales. A company's after-tax profit margin is important because it tells investors the percentage of money a company actually earns per dollar of sales. This ratio is interpreted in the same way as profit margin - the after-tax profit margin is simply more stringent because it takes taxes into account.

Investopedia explains After-Tax Profit Margin
Often, a company's earnings don't tell the entire story. The amount of profit can increase, but that doesn't mean the company's profit margin is improving. For example, a company's sales could increase, but if costs also rise, that leads to a lower profit margin than what the company had when it had lower profits. This is an indication that the company needs to better control its costs.