{
  "model": "wspolnota-zakup-v1-20261030",
  "published": "2026-10-30",
  "currency": "PLN",
  "assumptions": {
    "price_a": 640000,
    "price_b": 600000,
    "own_share": 0.2,
    "mortgage_nominal_annual_rate": 0.06,
    "discount_nominal_annual_rate": 0.06,
    "monthly_rate": 0.005,
    "mortgage_months": 300,
    "extra_monthly_fee": 500,
    "extra_fee_months": 120,
    "payment_timing": "end_of_month",
    "monthly_rounding": false,
    "excluded": [
      "transaction_costs",
      "taxes",
      "insurance",
      "rate_changes",
      "fee_changes",
      "property_resale_value",
      "renovation_value",
      "prepayments"
    ]
  },
  "results": {
    "mortgage_payment_a": 3298.823175605834,
    "mortgage_payment_b": 3092.6467271304696,
    "mortgage_payment_saving": 206.1764484753644,
    "extra_monthly_outflow_b": 293.8235515246356,
    "initial_own_funds_saving": 8000,
    "extra_fees_nominal": 60000,
    "extra_fees_present_value": 45036.72666358362,
    "discount_for_monthly_neutrality": 97004.29000448971,
    "extra_monthly_outflow_with_50000_discount": 242.27943940579416,
    "total_net_present_value_b_minus_a": 5036.726663583939
  },
  "periods": [
    {
      "months": 36,
      "nominal_total": 18000,
      "present_value": 16435.508119632635
    },
    {
      "months": 60,
      "nominal_total": 30000,
      "present_value": 25862.780375565482
    },
    {
      "months": 120,
      "nominal_total": 60000,
      "present_value": 45036.72666358362
    }
  ],
  "convention": "CSV difference = B minus A; positive means higher outflow for B. Month 0 is the own contribution; subsequent balances are after payment. Price compensation uses the same mortgage and discount rate and the full 300-month mortgage horizon.",
  "row_count": 301,
  "sources": [
    "https://eli.gov.pl/api/acts/DU/2026/232/text/T/D20260232L.pdf",
    "https://www.mbank.pl/pdf/firmy/kredyty/regulamin-kredytu-remontowego-dla-wspolnot-mieszkaniowych-obowiazuje-od-4-12-2020.pdf"
  ]
}