You must pay self-employment taxes if your net earnings were ________ or more.

Self-employment taxes are applicable when an individual's net earnings from self-employment reach or exceed a specific threshold. In this case, the correct amount is $400. This is the minimum net earnings from self-employment that triggers the requirement to pay self-employment taxes. It is important for self-employed individuals to be aware of this threshold because it reflects the IRS's regulation, which mandates that self-employed individuals must pay self-employment taxes on net earnings of at least $400, which contributes to Social Security and Medicare benefits.

Understanding this threshold is crucial for budgeting and tax planning. Knowing that income below this level does not require self-employment tax payment can help contractors and self-employed persons effectively manage their finances and ensure compliance with tax laws. Therefore, if an individual has net earnings of $400 or more, they are liable for these taxes, making $400 the correct choice.