# Mortgage Calculation API ## Introduction The Mortgage Calculation API returns a structured JSON response with a clear mortgage assessment. It is designed for mortgage advisors, banks, and developers who need reliable mortgage calculations, quickly and consistently. ## Key features Key aspects of the Mortgage Calculation API includes: * **Automatic property enrichment**: when you provide an address, the API retrieves the WOZ value and energy label. This removes the need to look up the property value manually. * **Nibud 2026 compliant**: calculations follow the official Nibud 2026 debt-service-to-income (DSTI) standards. * **Automatic interest rate:** if no interest rate is provided, the API fetches the current rate from DNB (De Netherlandsche Bank) automatically. * **Energy label support:** providing an energy label applies the official Nibud 2026 extra mortgage amounts and adjust the NHG limit where apploicable. * **Flexible input**: works with or without a property address. * With an address: the API uses property data such as the WOZ value. * Without an address: the API uses the provided purchase price. * Without an address and purchase price: the API performs an income-based calculation and returns the maximum mortgage. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.altum.ai/english/financing/mortgage-calculation-api.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.