# Create interest plan version

Create a new version of an existing interest plan. This endpoint allows you to update specific fields while preserving others from the previous version. 

Key features:
- Creates a new version with the specified `start_date`.
- Updates only the provided fields—any field not specified inherits the value from the previous version.
- Validates that the new `start_date` is after the `start_date` of the previous version.
- Maintains immutable fields like `interest_type` and `tier_calculation`.
- Preserves existing tiers when updating `interest_by_tiers`—only specified tiers are updated.

This endpoint generates an [Interest plan created](https://developers.pismo.io/events/docs/interest-engine-interest-plan-creation-success-1) event.


# OpenAPI definition

```json
{
  "openapi": "3.1.0",
  "info": {
    "title": "Banking - Interest engine",
    "version": "1.0.0",
    "description": "API to handle interest-bearing account operations",
    "termsOfService": "https://developers.pismo.io/terms/",
    "contact": {
      "name": "API Support",
      "url": "https://developers.pismolabs.io/pismo-docs/docs/support"
    },
    "license": {
      "name": "Copyright Pismo"
    }
  },
  "servers": [
    {
      "url": "https://sandbox.pismolabs.io/interest-engine",
      "description": "Sandbox API server for testing"
    },
    {
      "url": "https://sandbox.pismolabs.io/passport/v2/s2s/access-token",
      "description": "Sandbox API for oauth2"
    }
  ],
  "tags": [
    {
      "name": "Interest engine",
      "description": "Manage interest plans"
    }
  ],
  "components": {
    "parameters": {
      "Authorization": {
        "name": "authorization",
        "in": "header",
        "description": "Authorization",
        "required": true,
        "example": "Bearer YOUR_BEARER_TOKEN",
        "schema": {
          "type": "string"
        }
      },
      "ContentType": {
        "name": "content-type",
        "in": "header",
        "description": "Content type",
        "required": true,
        "example": "application/json",
        "schema": {
          "type": "string"
        }
      },
      "InterestPlanIdPath": {
        "name": "interestPlanId",
        "in": "path",
        "description": "Interest plan ID generated during the plan's creation. Must be an alphanumeric UUID with the alphabetical characters in lowercase.",
        "required": true,
        "example": "d9b2c9e1-4633-4a10-841b-270f7f1493cd",
        "schema": {
          "type": "string"
        }
      }
    },
    "schemas": {
      "Amount": {
        "type": "number",
        "format": "double",
        "description": "Amount in the `interest_by_tier`",
        "example": 1000
      },
      "CapEffectiveRate": {
        "type": "number",
        "format": "double",
        "description": "Cap effective rate. If you provide a value for `cap_effective_rate`, you must also provide a value for `cap_threshold`.",
        "example": 1.2
      },
      "CapThreshold": {
        "type": "number",
        "format": "double",
        "description": "Cap threshold value. If you provide a value for `cap_threshold`, you must also provide a value for `cap_effective_rate`.",
        "example": 1.1
      },
      "Days": {
        "type": "integer",
        "format": "int32",
        "description": "Number of days in `interest_by_tier`",
        "example": 30
      },
      "Description": {
        "type": "string",
        "description": "Interest plan name",
        "example": "Banking plan"
      },
      "FixedInterestRate": {
        "type": "number",
        "format": "float",
        "description": "Fixed annual interest rate for investments or deposits. If a `benchmark` value is provided, this field must be null.",
        "example": 0.1
      },
      "FloorEffectiveRate": {
        "type": "number",
        "format": "double",
        "description": "Floor effective rate",
        "example": 2.2
      },
      "FloorThreshold": {
        "type": "number",
        "format": "double",
        "description": "Floor threshold value",
        "example": 2.1
      },
      "InterestByTiers": {
        "type": "object",
        "properties": {
          "type": {
            "$ref": "#/components/schemas/InterestByTiersType"
          },
          "tier_calculation": {
            "$ref": "#/components/schemas/TierCalculation"
          },
          "tiers": {
            "type": "array",
            "items": {
              "$ref": "#/components/schemas/InterestByTiersArrayObject"
            }
          }
        },
        "required": [
          "type",
          "tier_calculation",
          "tiers"
        ],
        "description": "Interest by tiers configuration",
        "example": {
          "type": "TERM",
          "tier_calculation": "RETROACTIVE",
          "tiers": [
            {
              "days": 30,
              "amount": 1000,
              "margin_rate": 1,
              "fixed_interest_rate": 1.2
            },
            {
              "days": 60,
              "amount": 2000,
              "margin_rate": 1,
              "fixed_interest_rate": 1.3
            }
          ]
        }
      },
      "InterestByTiersArrayObject": {
        "type": "object",
        "properties": {
          "days": {
            "$ref": "#/components/schemas/Days"
          },
          "amount": {
            "$ref": "#/components/schemas/Amount"
          },
          "margin_rate": {
            "$ref": "#/components/schemas/MarginRate"
          },
          "fixed_interest_rate": {
            "$ref": "#/components/schemas/FixedInterestRate"
          }
        },
        "description": "Tier details for interest calculation"
      },
      "InterestByTiersType": {
        "type": "string",
        "description": "Interest type\n- `TERM`: Interest rate varies according to the period of time since the deposit was made.\n- `AMOUNT`: Interest rate varies according to the current balance.\n",
        "enum": [
          "TERM",
          "AMOUNT"
        ],
        "example": "TERM"
      },
      "InterestPlanId": {
        "type": "string",
        "format": "UUID",
        "description": "Interest plan ID generated during the plan's creation. Must be an alphanumeric UUID with the alphabetical characters in lowercase.",
        "example": "07d84f79-3027-47bd-b628-65528ccc8fb2"
      },
      "InterestPlanVersionRequest": {
        "title": "Interest plan version request",
        "type": "object",
        "properties": {
          "start_date": {
            "$ref": "#/components/schemas/StartDateForNewVersion"
          },
          "description": {
            "$ref": "#/components/schemas/Description"
          },
          "fixed_interest_rate": {
            "$ref": "#/components/schemas/FixedInterestRate"
          },
          "margin": {
            "$ref": "#/components/schemas/Margin"
          },
          "margin_rate": {
            "$ref": "#/components/schemas/MarginRate"
          },
          "interest_by_tiers": {
            "$ref": "#/components/schemas/InterestByTiers"
          },
          "interest_thresholds": {
            "$ref": "#/components/schemas/InterestThresholds"
          }
        },
        "required": [
          "start_date"
        ],
        "example": {
          "start_date": "2025-06-17",
          "description": "BANKING PLAN v2",
          "margin": 0.05,
          "margin_rate": 1.2
        }
      },
      "InterestPlanVersionResponse": {
        "title": "Interest plan version response",
        "type": "object",
        "properties": {
          "interest_plan_id": {
            "$ref": "#/components/schemas/InterestPlanId"
          },
          "version": {
            "type": "string",
            "description": "ID for the new interest plan version",
            "example": "2025-06-17"
          }
        }
      },
      "InterestThresholds": {
        "type": "object",
        "properties": {
          "cap_threshold": {
            "$ref": "#/components/schemas/CapThreshold"
          },
          "cap_effective_rate": {
            "$ref": "#/components/schemas/CapEffectiveRate"
          },
          "floor_threshold": {
            "$ref": "#/components/schemas/FloorThreshold"
          },
          "floor_effective_rate": {
            "$ref": "#/components/schemas/FloorEffectiveRate"
          }
        },
        "description": "Cap and floor thresholds for the interest plan",
        "example": {
          "interest_thresholds": {
            "cap_threshold": 1.1,
            "cap_effective_rate": 1.2,
            "floor_threshold": 2.2,
            "floor_effective_rate": 2.1
          }
        }
      },
      "Margin": {
        "type": "number",
        "format": "double",
        "description": "Also known as a spread, this is an incremental rate the clients receive on investments or deposits. \nIf a `benchmark` value is provided, this field is optional.\nIf `benchmark` is null, this field must be null also.\n",
        "example": 0.02
      },
      "MarginRate": {
        "type": "number",
        "format": "double",
        "description": "Rate linked to the benchmark rate. For example, for 110% FED, margin rate is 110%. If a `benchmark` value is not provided, this field must be null.",
        "example": 1.1
      },
      "StartDateForNewVersion": {
        "type": "string",
        "format": "date",
        "description": "Date to start applying the new interest plan version. Format = YYYY-MM-DD. Must be greater than or equal to current date.",
        "example": "2025-06-17"
      },
      "TierCalculation": {
        "type": "string",
        "description": "Tier calculation method\n- `RETROACTIVE`: Interest is recalculated from the beginning based on the new applicable rate.\n- `NON-RETROACTIVE`: Interest is calculated progressively based on each layer rate.\n",
        "enum": [
          "RETROACTIVE",
          "NON-RETROACTIVE"
        ],
        "example": "RETROACTIVE"
      }
    },
    "securitySchemes": {
      "BearerAuth": {
        "type": "http",
        "scheme": "bearer",
        "bearerFormat": "JWT"
      }
    },
    "responses": {
      "400BadRequest": {
        "description": "Bad request"
      },
      "404NotFound": {
        "description": "Not found"
      },
      "409Conflict": {
        "description": "Conflict - A version with this start_date already exists"
      },
      "500InternalServerError": {
        "description": "Internal server error"
      }
    }
  },
  "security": [
    {
      "BearerAuth": []
    }
  ],
  "paths": {
    "/v1/interest/plan/{interestPlanId}": {
      "patch": {
        "summary": "Create interest plan version",
        "description": "Create a new version of an existing interest plan. This endpoint allows you to update specific fields while preserving others from the previous version. \n\nKey features:\n- Creates a new version with the specified `start_date`.\n- Updates only the provided fields—any field not specified inherits the value from the previous version.\n- Validates that the new `start_date` is after the `start_date` of the previous version.\n- Maintains immutable fields like `interest_type` and `tier_calculation`.\n- Preserves existing tiers when updating `interest_by_tiers`—only specified tiers are updated.\n\nThis endpoint generates an [Interest plan created](https://developers.pismo.io/events/docs/interest-engine-interest-plan-creation-success-1) event.\n",
        "tags": [
          "Interest engine"
        ],
        "operationId": "patch-v1-interest-plan",
        "parameters": [
          {
            "$ref": "#/components/parameters/Authorization"
          },
          {
            "$ref": "#/components/parameters/ContentType"
          },
          {
            "$ref": "#/components/parameters/InterestPlanIdPath"
          }
        ],
        "requestBody": {
          "description": "Request body",
          "required": true,
          "content": {
            "application/json": {
              "schema": {
                "$ref": "#/components/schemas/InterestPlanVersionRequest"
              }
            }
          }
        },
        "responses": {
          "200": {
            "description": "OK",
            "content": {
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/InterestPlanVersionResponse"
                }
              }
            }
          },
          "400": {
            "$ref": "#/components/responses/400BadRequest"
          },
          "404": {
            "$ref": "#/components/responses/404NotFound"
          },
          "409": {
            "$ref": "#/components/responses/409Conflict"
          },
          "500": {
            "$ref": "#/components/responses/500InternalServerError"
          }
        }
      }
    }
  }
}
```