> For the complete documentation index, see [llms.txt](https://flapjax.gitbook.io/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://flapjax.gitbook.io/docs/hosting/cost-optimisation/editor.md).

# VAT / Tax Registration

Improper VAT/TRN configuration can add unnecessary 25% tax to AWS bills.

Why VAT/TRN Configuration Matters

AWS defaults to tax based on billing address unless a TRN is provided.

### How to Configure VAT / TRN

1. Go to **Billing → Tax Settings → Manage Tax Registration**
2. Enter:
   * Country
   * VAT/TRN
   * Legal business name
   * Address (must match TRN country)
3. Upload exemption certificates if applicable.

### Common Issues

* Address country mismatch
* Missing TRN
* Incorrect contact/billing address

### Summary

Correct VAT configuration prevents unnecessary tax charges.