Contact Us
We welcome feedback, bug reports, and suggestions. Below you'll find the right contact for your inquiry.
Calculation Error Reports
Found a calculation error? Please include the following information so we can investigate quickly:
- Page URL: The exact URL of the calculator page
- Input values: The values you entered (salary, tax class, state, etc.)
- Expected result: What result you expected and why (e.g., "My tax return shows €X")
- Source: Official source you're comparing against (e.g., IRS publication, BMF-PAP, Lohnsteuerbescheinigung)
Response time: We aim to respond within 3–5 business days. Complex investigations may take longer.
Privacy Inquiries
For questions about data collection, cookies, or our privacy policy:
Advertising & Partnerships
For advertising inquiries, custom calculator development, or partnership opportunities:
General Feedback & Feature Requests
Have an idea for a new calculator or improvement? We'd love to hear from you:
What We Can Help With
The fastest way to improve NumBoxHub is precise feedback. We review reports about incorrect formulas, outdated tax parameters, unclear disclaimers, broken links, accessibility issues, mobile layout problems, and missing source references. If you are comparing one of our calculators with an official government worksheet or a payroll document, include the exact source and the input assumptions used.
Please do not send sensitive personal documents, full Social Security numbers, tax IDs, bank details, payslips, or private medical information. Our calculators are designed to run locally in your browser, and we do not need personal records to investigate most issues.
Editorial & Source Corrections
For tax and finance content, we prioritize corrections that cite primary sources such as the IRS, SSA, U.S. state revenue departments, Bundesfinanzministerium, GKV-Spitzenverband, Deutsche Rentenversicherung, or the relevant statute. When a rule changes, we update the affected calculator, refresh its verification date, and keep the page language clear about whether the result is an exact formula or a planning estimate.
Response Times
- Calculation errors: 3–5 business days (investigation may take longer)
- Privacy requests: Within 30 days (as required by GDPR)
- Advertising inquiries: 1–2 business days
- Feature requests: 5–7 business days