Enforcement challenges for collecting excess sales tax include:

Administrative Challenges

1. Limited Resources: Insufficient staff, funding, and technology can hinder effective enforcement.
2. Complexity of Tax Laws: Ever-changing tax laws and regulations can make enforcement difficult.
3. Data Management: Managing large datasets to identify non-compliance can be challenging.

Technical Challenges

1. Tax Evasion Techniques: Sophisticated tax evasion techniques, such as ghosting or phishing, can evade detection.
2. Digital Tax Evasion: E-commerce and digital services can make it difficult to track and collect sales tax.
3. Cryptocurrency Transactions: Anonymous nature of cryptocurrency transactions can make enforcement challenging.

Compliance Challenges

1. Voluntary Compliance: Relying on businesses to voluntarily comply with sales tax laws can lead to non-compliance.
2. Taxpayer Education: Educating taxpayers about their obligations can be resource-intensive.
3. Non-Compliant Businesses: Dealing with non-compliant businesses can be time-consuming and challenging.

International Challenges

1. Cross-Border Transactions: Enforcing sales tax on international transactions can be complex.
2. Tax Havens: Dealing with businesses that use tax havens to avoid sales tax can be challenging.
3. International Cooperation: Collaborating with international authorities to enforce sales tax laws can be difficult.

Legal Challenges

1. Tax Disputes: Resolving tax disputes with businesses can be time-consuming and costly.
2. Tax Litigation: Pursuing tax litigation can be resource-intensive and uncertain.
3. Constitutional Challenges: Dealing with constitutional challenges to sales tax laws can be complex.

To overcome these challenges, tax authorities can consider:

1. Investing in technology and data analytics
2. Enhancing taxpayer education and outreach
3. Improving international cooperation and collaboration
4. Strengthening tax laws and regulations
5. Increasing resources and funding for enforcement activities