> For the complete documentation index, see [llms.txt](https://docs.altum.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.altum.ai/financieren/hypotheekberekening-api/authenticatie-invoer-en-resultaat.md).

# Authenticatie, invoer en resultaat

### Bereken de hypotheek voor een Nederlandse woning

{% tabs %}
{% tab title="v1" %} <mark style="color:$success;">\*\*\`POST\`\*\*</mark> \`<https://api.altum.ai/v1/mortgage-calculator\\`>

#### Headers

<table><thead><tr><th width="258.1484375">Naam</th><th width="199.80078125">Type</th><th>Omschrijving</th></tr></thead><tbody><tr><td>x-api-key<mark style="color:red;">*</mark></td><td>string</td><td>Unieke API-sleutel van Altum. Maak er één aan op <a href="https://platform.altum.ai/auth">https://platform.altum.ai</a></td></tr><tr><td>Content-Type</td><td>string</td><td>application/json</td></tr></tbody></table>

#### Request Body

Let op verplichte velden: een request moet minstens één van de volgende aanleveren: ofwel gross\_annual\_income (voor hypotheekberekening), ofwel loan\_amount en nominal\_interest\_rate (voor losse JKP/APR-berekening).

<table><thead><tr><th width="252.66796875">Naam</th><th width="199.78125">Type</th><th>Omschrijving</th></tr></thead><tbody><tr><td>postcode</td><td>string</td><td>Postcode van het object in 4-cijfers + 2-letters formaat (bijv. "1234AB")</td></tr><tr><td>housenumber</td><td>number</td><td>Huisnummer van het object</td></tr><tr><td>houseaddition</td><td>string</td><td>Huisletter en toevoeging van het object</td></tr><tr><td>loan_amount<mark style="color:red;">*</mark></td><td>number</td><td>Hoofdsom van de lening in € voor de JKP/APR-berekening. Moet groter zijn dan de initiële kosten</td></tr><tr><td>nominal_interest_rate<mark style="color:red;">*</mark></td><td>number</td><td>Nominale jaarlijkse rente in %</td></tr><tr><td>initial_costs</td><td>number</td><td>Totale eenmalige kosten bij start</td></tr><tr><td>gross_annual_income<mark style="color:red;">*</mark></td><td>number</td><td>Bruto jaarinkomen van de hoofdaanvrager (in €)</td></tr><tr><td>partner_gross_income</td><td>number</td><td>Bruto jaarinkomen van de partner (in €). Standaard 0</td></tr><tr><td>applicant_type</td><td>string</td><td>"single" of "couple". Beïnvloedt de €17.000 alleenstaande-bonus. Standaard "single"</td></tr><tr><td>existing_debts</td><td>number</td><td>Maandelijkse bestaande schuldenverplichtingen (in €). Verlaagt het leenbedrag. Standaard 0</td></tr><tr><td>student_loan</td><td>number</td><td>Maandelijkse studieschuld (in €). Verlaagt het leenbedrag. Standaard 0</td></tr><tr><td>interest_rate</td><td>number</td><td>Jaarlijkse rente als percentage (bijv. 3.5 voor 3,5%)</td></tr><tr><td>mortgage_type</td><td>string</td><td>"annuity" of "linear"</td></tr><tr><td>loan_term_years</td><td>number</td><td>Looptijd van de lening in jaren. Maximum is 30</td></tr><tr><td>purchase_price</td><td>number</td><td>Aankoopprijs (in €). Wordt gebruikt als marktwaarde als adresverrijking geen WOZ-waarde vindt</td></tr><tr><td>down_payment</td><td>number</td><td>Eigen middelen om de hoofdsom te verlagen (in €). Standaard 0</td></tr><tr><td>fixed_rate_period</td><td>number</td><td>Aantal jaren dat de rente vaststaat</td></tr><tr><td>nhg_eligible</td><td>boolean</td><td>Of NHG van toepassing is. Indien weggelaten, automatisch afgeleid: true bij aankoopprijs ≤ €470.000</td></tr><tr><td>first_time_buyer</td><td>boolean</td><td>True als de hoofdaanvrager een starter is. Beïnvloedt de overdrachtsbelasting. Standaard false</td></tr><tr><td>applicant_age</td><td>number</td><td>Leeftijd van de hoofdaanvrager. Verplicht voor starter-vrijstelling overdrachtsbelasting</td></tr><tr><td>partner_age</td><td>number</td><td>Leeftijd van de partner. Verplicht voor starter-vrijstelling overdrachtsbelasting bij couple</td></tr><tr><td>energy_label</td><td>string</td><td>Energielabel van de woning (E/F/G/C/D/A/B/A+/A++/A+++/A++++/A++++_warranty). Beïnvloedt extra hypotheekbedrag en NHG-grens</td></tr><tr><td>sustainability_measures</td><td>boolean</td><td>True als verduurzamingsmaatregelen van de TRHK-lijst in de hypotheek zitten. Beïnvloedt renovatiebonus en NHG-grens. Standaard false</td></tr><tr><td>table_type</td><td>string</td><td>Nibud DSTI-tabel. Een van: "non_aow_box1" (standaard), "aow_box1", "non_aow_box3", "aow_box3"</td></tr></tbody></table>

{% tabs %}
{% tab title="200: OK Successful response" %}

```json
{
	"postcode": "9636AA",
	"housenumber": 5,
	"houseaddition": null,
	"max_mortgage_amount": 378000.0,
	"max_mortgage_by_income": 400881.24,
	"principal": 378000.0,
	"monthly_payment_gross": 1778.58,
	"monthly_payment_net": 1320.5,
	"total_interest_paid": 262287.87,
	"total_costs": 650047.87,
	"transfer_tax": 7560.0,
	"transfer_tax_rate_used": 0.02,
	"affordability_ratio": 0.2511,
	"nhg_compliance": true,
	"annual_percentage_rate": "4.09%",
	"term_months": 360,
	"total_initial_costs": 3000.0,
	"net_credit_amount": 34542.0,
	"monthly_payment": 165.25,
	"rate_used": 3.88,
	"rate_fetched_from": "dnb",
	"effective_rate_used": 3.88,
	"loan_term_years": 30,
	"mortgage_type": "annuity",
	"dsti_ratio_used": 0.255,
	"table_type_used": "non_aow_box1",
	"single_bonus_applied": 17000.0,
	"energy_label_bonus": 0.0,
	"renovation_bonus": 0.0,
	"debt_deduction_applied": 0.0,
	"data_enrichment_status": "enriched",
	"enrichment_data": {
		"found": true,
		"woz_latest": 378000.0,
		"woz_latest_year": 2024,
		"energy_label": "F"
	},
	"warnings": [
		"Income allows a higher mortgage, but you are capped at the NHG mortgage cap of €450,000."
	],
	"metadata": {
		"table_type": "non_aow_box1",
		"dsti_ratio_used": 0.255,
		"effective_rate_used": 3.88,
		"nhg_price_limit": 470000,
		"nhg_mortgage_cap": 450000.0,
		"energy_label_bonus": 0.0,
		"renovation_bonus": 0.0,
		"single_bonus_applied": 17000.0,
		"mortgage_interest_deduction_rate": 0.3748,
		"notary_cost": 1500.0,
		"appraisal_cost": 700.0,
		"market_value_source": "woz",
		"market_value_used": 378000.0,
		"market_value_note": "WOZ used — no purchase_price provided",
		"evaluation_date": "20260930"
	}
}
```

{% endtab %}

{% tab title="400: Bad Request" %}

```json
{
  "error": "Unable to process mortgage calculation at this time."
}
```

{% endtab %}

{% tab title="401: Unauthorized" %}

```json
{
  "output": "Please use https://api.altum.ai or visit https://mopsus.altum.ai to make your request."
}
```

{% endtab %}

{% tab title="403: Forbidden" %}

```json
{
  "message": "Forbidden"
}
```

{% endtab %}

{% tab title="500: Internal Server Error Service is not available and/or down" %}

```json
{
  "message": "Internal server error"
}
```

{% endtab %}

{% tab title="422: Unprocessable Entity" %}

```json
{
  "detail": [
    {
      "type": "value_error",
      "msg": "applicant_type must be \"single\" or \"couple\"."
    }
  ]
}
```

{% endtab %}
{% endtabs %}

### Request body

#### Voorbeeld request

```json
{
  "postcode": "9636AA",
  "housenumber": 5,
  "gross_annual_income": 85000,
  "mortgage_type": "annuity",
  "loan_term_years": 30,
	"loan_amount": 37542, 
 	"nominal_interest_rate": 3.34 
}
```

{% endtab %}
{% endtabs %}


---

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