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Invoice-based payment inflow forecast

Cashflow Forecast API for Open Invoices

Retrieve expected incoming payments, open receivables, and overdue invoices as structured data for dashboards and automation.

The outlook is based on invoices stored in QuoteCash, their due dates, open amounts, and recorded payments.

GET endpointWeekly or monthly bucketsInvoice drill-down
01QuoteCash

Expected payment inflows

The endpoint returns expected incoming payments together with open and overdue amounts, grouped by week or month.

02QuoteCash

Invoice and payment data

The response uses stored invoice totals, due dates, open balances, recorded payments, and partial-payment state. Document generator endpoints do not store invoices automatically.

03QuoteCash

Invoice detail

Passing include_invoices=true returns paginated invoice rows with paymentState, isOverdue, openAmount, and reminder metadata.

How it works

How the invoice-based cashflow forecast works

QuoteCash exposes GET /api/v1/cashflow/forecast as a business-scoped endpoint. It returns normalized range metadata, active filters, summary totals, and weekly or monthly buckets for expected incoming payments, paid amounts, overdue balances, and open balances.

For current and future periods, the public endpoint groups remaining open invoice amounts by invoice due date. It does not use machine learning or promise a customer-specific payment date. Recorded payment history is used to report paid amounts and reconstruct past-period values.

This is the stored-invoice slice of the API. POST /api/v1/invoices writes invoices and customer mappings into the business attached to the API key, while POST /api/v1/invoices/xrechnung, /peppol, and /zugferd remain create-and-return endpoints for teams that want to handle storage themselves.

When include_invoices=true is passed, the response also adds paginated invoice rows. Each row includes payment state, overdue status, open amount, and reminder metadata, so dashboards and automation flows can move from forecast totals to an overdue attention list without scraping the UI.

The endpoint supports payment_state and reminder_stage filters, sorting, pagination, and explicit business_id matching. All forecast amounts are currently processed and returned in euro (EUR). Currency conversion and multi-currency aggregation are not supported.

Who it’s for

Who is the API for?

Freelancers and small businesses

Freelancers can review expected invoice payments and overdue balances without rebuilding an accounts receivable list in a spreadsheet.

SaaS developers

Products for billing or finance workflows need a stable API for background jobs, dashboards, and internal tools.

Agencies and automation partners

Agencies using Make.com or n8n need explicit filters and stable JSON rather than human-only cashflow reports.

ERP integrators

Integrators need scoping guarantees and drill-down data. Matching the API key to the business and exposing reminder state reduces custom authorization work.

Editorial note

Last reviewed: July 24, 2026

Why QuoteCash exposes payment inflows as API data

QuoteCash manages invoices, payment state, due dates, open balances, and reminder metadata. Those operational records provide a consistent source for dashboards and receivables workflows.

Implementation guidance

What this payment inflow forecast covers

The public API shows expected incoming payments from stored invoices. For current and future periods, remaining open amounts are grouped into weeks or months by invoice due date. Overdue receivables, paid amounts, and recorded partial payments are reported separately.

This is not a complete financial or liquidity forecast. It does not include future operating expenses, payroll, taxes, rent, subscriptions, planned purchases, uninvoiced sales, or bank-account balances.

  • Included: invoice total, open and paid amounts, and due date.
  • Included: open, partially paid, paid, and overdue payment states.
  • Optional: invoice rows and reminder metadata for drill-down views.
  • Excluded: expense planning, bank forecasting, and complete P&L or liquidity scenarios.
Implementation guidance

Use cases for receivables and workflow automation

Agencies and service businesses can review which invoice amounts are due this week and which receivables are already overdue. SaaS and ERP teams can join open balances to internal customer or contract records.

Optional invoice rows explain each period total by customer, amount, due date, payment state, and reminder metadata. That supports accounts receivable dashboards, collection workflows, and regular payment inflow reporting.

Implementation guidance

From forecast totals to invoice detail

With include_invoices=true, the API supplements period totals with paginated invoice rows containing paymentState, isOverdue, openAmount, and reminder metadata. Teams can trace an exception directly to the underlying invoice.

Filters, sorting, and reminder_stage support focused work queues, such as overdue invoices that have reached a specific reminder stage.

Implementation guidance

A practical API-oriented workflow

A scheduled request can refresh open and overdue amounts in dashboards, BI tools, or internal alerts. Teams combine the date range, grouping, and payment-state filters to match each operational workflow.

Example

API example: retrieve overdue forecast detail

The endpoint can return period buckets and invoice rows, making it suitable for dashboards and automation workflows.

GET /api/v1/cashflow/forecast?from=2026-07-01&to=2026-09-30&groupBy=week&payment_state=overdue&include_invoices=true
Authorization: Bearer <api_key>
{
  "range": { "groupBy": "week", "currency": "EUR" },
  "summary": { "openAmount": 8400, "overdueAmount": 2200, "paidAmountInRange": 5100 },
  "periods": [],
  "invoices": [{ "invoiceNumber": "INV-2026-1042", "openAmount": 2200, "currency": "EUR", "paymentState": "overdue", "isOverdue": true }],
  "pagination": { "page": 1, "perPage": 25, "totalItems": 1, "totalPages": 1 }
}
  • Dashboard: visualize expected and overdue amounts by week.
  • Automation: send overdue invoice summaries to finance for review.
  • Back office: connect invoice risk to customer name and reminder state.
View API documentationStart for free
Implementation

Payment inflow forecast API checklist

  1. 1Decide which invoice states belong in the forecast.
  2. 2Keep due dates, open amounts, and partial payments accurate.
  3. 3Choose a forecast range and grouping that matches the operating rhythm.
  4. 4Filter overdue invoices separately from normal expected cash.
  5. 5Use reminder stage and invoice/customer fields to prioritize action.
  6. 6Run the forecast regularly instead of relying on manual exports.

Related QuoteCash pages

API documentationReview endpoint behavior, authentication, and example payloads.XRechnung APICombine e-invoicing generation and receivables visibility in one API-first invoice stack.

Frequently Asked Questions

What is a payment inflow forecast?
It is an invoice-based outlook of expected incoming payments. QuoteCash groups open invoice amounts by due date and also reports overdue, paid, and open totals.
Which data does the Cashflow Forecast API use?
The public endpoint uses stored invoice totals, due dates, open and paid amounts, payment state, recorded payments, and reminder metadata. It does not use bank-account or expense data.
Does the forecast include future expenses?
No. It focuses on expected incoming payments from existing invoices. Salaries, taxes, rent, subscriptions, planned purchases, and bank balances are not part of the forecast.
Are partial payments and overdue invoices included?
Yes. Open amounts reflect recorded payments, including partial payments, and overdue invoice balances are reported separately. The payment_state filter supports open, partially_paid, paid, and overdue values.
Can the API return invoice-level detail?
Yes. Passing include_invoices=true returns paginated invoice rows so dashboards and automation tools can link forecast totals back to individual invoices.
Do generated e-invoices automatically appear in cashflow?
No. POST /api/v1/invoices/xrechnung, /peppol, and /zugferd return temporary XML or PDF artifacts without storing an invoice or customer relationship. Use the app or POST /api/v1/invoices when you want QuoteCash to persist the invoice, map the customer, and include it in cashflow.
Can I scope the forecast to a specific business?
Each API key belongs to one business. An optional business_id must match that assignment; a mismatch returns 403 and cannot be used to access another business.
Is this endpoint useful for Make.com or n8n workflows?
Yes. It is a normal GET endpoint with date filters, grouping, and optional invoice detail, so it fits scheduled polling or dashboard sync workflows in automation tools.
Is this a complete business cashflow forecast?
No. It is an accounts receivable and payment inflow forecast based on stored invoice data. A complete cashflow forecast would also need future expenses, non-invoice income, and bank balances.
Is a payment inflow forecast the same as accounting software?
No. It provides operational visibility from invoice and payment data. It does not replace bookkeeping, tax reporting, or complete financial and liquidity planning.
Which currency does the Cashflow Forecast API support?
The Cashflow Forecast API currently supports euro (EUR) only. Currency conversion and consolidated multi-currency reporting are not currently part of the API.
Why use an API instead of CSV exports?
An API can run on a schedule, filter results, power dashboards, and trigger automation. CSV exports usually become stale immediately.
Can this work for Make.com or n8n workflows?
Yes. A normal authenticated GET endpoint is a good fit for scheduled polling, alerts, and dashboard sync jobs.