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Rechnungskit
Rechnungskit vs. Fynn

Fynn or Rechnungskit: full subscription suite or invoicing layer

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Rechnungskit turns every payment that runs through your Stripe, Mollie, PayPal or Unzer account or your shop into an e-invoice under EN 16931. The invoice is locked in the GoBD archive, and revenue, fees and payouts go to your tax advisor as DATEV bookings, plus deferred revenue if you prepare balance sheets. Rechnungskit bills simple monthly and annual subscriptions itself via subscription links, with a customer portal for cancellation and withdrawal; existing Stripe Billing subscriptions move over at the end of their period. Fynn is a complete billing platform for B2B SaaS. Quote, contract, usage-based billing, invoice, SEPA collection, dunning, deferred revenue and DATEV export all run in one system there; Stripe and PayPal only serve as payment methods.

Sources checked: October 2, 2026 · Updated: October 2, 2026 · No guarantee of accuracy · Sources below the table

The short version

Rechnungskit fits if …

your payments run through Stripe, Mollie, PayPal or a shop and should stay that way, but every payment has to become an e-invoice with your own number sequence, a GoBD archive entry and a finished DATEV booking including fees. Add OSS, the qualified VAT ID check and a price per document instead of a monthly package.

Fynn fits if …

you close B2B contracts with quotes, approvals and e-signatures, bill on usage or a hybrid model and need dunning, SEPA business direct debit through your house bank, or HubSpot and Salesforce sync. That's what a platform from €149 a month is built for, and Rechnungskit doesn't have these tools.

Fynn replaces your billing; Rechnungskit builds on the billing you already have. At Fynn, contract, invoice, collection and dunning run in one system, with Stripe only as the route for card payments. Rechnungskit leaves Stripe, Mollie, PayPal and your shop as they are and turns every payment into a compliant document and booking. It bills simple subscriptions itself, but not quotes or usage-based billing.

Rechnungskit and Fynn in detail

Every row is backed by a source. Where something couldn't be confirmed from public sources, the table says so.

Feature comparison of Rechnungskit and Fynn, as of October 2, 2026
Feature RechnungskitFynn
E-invoicing
ZUGFeRD 2.x / Factur-X outgoing Yes ZUGFeRD 2.5 under EN 16931, every invoice Status: included Yes1 every invoice, cancellation and credit note automatically as a ZUGFeRD PDF under EN 16931 (Fynn says ZUGFeRD 2.1), in all plans Status: included, see footnote 1
XRechnung for public-sector buyers Yes XRechnung 3.0 automatically as soon as the customer has a Leitweg-ID (public-sector routing ID) on file Status: included Yes1 can be enabled per customer, with Leitweg-ID; sending via Peppol in private beta (Revenue Platform plan) Status: included, see footnote 1
Validation before sending Mandatory fields under §14 UStG, tax rates, format rules Yes every invoice before sending (Mustang/EN 16931) Status: included Not documented2 Fynn validates the DATEV export before handover; an EN 16931 check of every e-invoice before sending is not documented Status: no reliable source found, see footnote 2
Receive and process e-invoices No deliberately out of scope. Rechnungskit creates outgoing invoices Status: not available Not documented1 Fynn only describes outgoing invoices Status: no reliable source found, see footnote 1
Shop automation
Own checkout link without a shop One-time purchase and subscription: whose name, whose payment provider Yes, in your name checkout.rechnungskit.de/c/… for one-time purchases, /s/… per subscription plan; payment through your Mollie, Stripe, PayPal or Unzer account straight to your bank account, e-invoice right after payment Status: included Yes, checkout link2 checkout link per product for one-time and recurring products, with discount codes, trial period and terms; payment runs through the payment methods connected in Fynn Status: included, see footnote 2
Native shop and payment integrations no third-party tools Yes Shopify, WooCommerce and Shopware natively, Stripe/Mollie/PayPal/Unzer, own checkout link for one-time purchases and subscriptions without a shop, own push API Status: included Payment methods, no shop1 Stripe (card), PayPal, GoCardless, own SEPA direct debit and EBICS, plus HubSpot, Salesforce and Attio; a connection to Shopify, WooCommerce or Shopware is not documented Status: limited, see footnote 1
Invoicing on the correct date of supply shipping date instead of payment date, automatically Yes from the shop's shipping event; for subscriptions, the service period comes from the billing period Status: included Period from the subscription2 revenue is booked to the right period based on the service period; a shipping event as the date of supply is not documented Status: limited, see footnote 2
Automatic cancellation invoices on refunds including partial refunds Yes to the cent, with its own correction document Status: included Yes, from Fynn2 a refund in Fynn creates the credit note and triggers the refund via Stripe or PayPal; cancellation only for unpaid invoices. The help center does not describe partial amounts separately Status: included, see footnote 2
Payout reconciliation with fees Stripe, Mollie, PayPal and others as finished bookings Yes fees and payouts as bookings Status: included Bank matching1 bank matching and matching of open items (from Quote-to-Cash); payment provider fees and payouts as separate bookings are not documented Status: limited, see footnote 1
Tax compliance
OSS / EU distance selling Yes destination-country rates, monitoring of the €10,000 threshold, export Status: included Not documented2 website and help center do not mention an OSS procedure Status: no reliable source found, see footnote 2
EU tax rates updated automatically Yes monthly from the EU database TEDB, with change alerts Status: included Not documented1 VAT and reverse charge are configured; automatic maintenance of EU tax rates is not documented Status: no reliable source found, see footnote 1
Qualified VAT ID (USt-IdNr.) check with evidence archive Yes qualified check with the BZSt (Federal Central Tax Office), response archived for 8 years Status: included Not documented1 reverse charge is configurable; a VAT ID check with the BZSt or via VIES is not documented Status: no reliable source found, see footnote 1
Single- and multi-purpose vouchers (§3 (13) to (15) UStG) Yes own voucher and store-credit register Status: included Not documented2 vouchers at Fynn are discount codes; single- and multi-purpose vouchers under § 3 (13) to (15) UStG are not mentioned Status: no reliable source found, see footnote 2
Deferred revenue (pRAP) / revenue recognition for subscriptions Yes pRAP for subscriptions and annual licenses Status: included Yes, a strength2 pRAP under HGB automatically: created from the net amount, released monthly, reversed on cancellation, month-end close; the bookings are part of the DATEV export Status: included, see footnote 2
DATEV & archive
Finished DATEV booking records not just document images Yes EXTF for SKR03/SKR04, revenue + payments + fees; document images via Beleglink in the "Belegtransfer" package for Unternehmen online Status: included Yes2 booking batches, debtor master data and document images for SKR03 and SKR04, as a download or automatically via DATEVconnect online Status: included, see footnote 2
GoBD archive with locking (Festschreibung) Yes WORM archive, SHA-256, locked from creation Status: included Provider's claim1 archiving "unchangeable, audit-proof" on servers in Germany according to Fynn, locking on DATEV export, locked month-end closes; an audit certificate is not mentioned in the sources checked Status: limited, see footnote 1
Free access for your tax advisor Yes own tax advisor portal, documents read-only Status: included Tax advisor portal2 own access with documents and DATEV reports, enabled per organization via support; Fynn doesn't say whether it costs extra Status: included, see footnote 2
Accounting & operations
VAT return (UStVA) / cash-basis accounts (EÜR) / direct ELSTER filing EC Sales List (ZM) import files are covered separately ZM data ZM import file yes; UStVA, EÜR and direct ELSTER filing stay with your tax advisor Status: limited No1 by its own description not accounting software, Fynn "does not replace accounting"; UStVA and EÜR stay with your tax advisor, same as Rechnungskit Status: not available, see footnote 1
Entry price from €9 base fee + tiered price per document; free to test in sandbox mode Status: included from €149/month3 Billing €149 paid monthly, €129 paid annually, €100,000 revenue a month included, 0.9% above that; Quote-to-Cash €399, Revenue Platform €799; unlimited invoices Status: note, see footnote 3
API for your own systems Yes push API in every plan Status: included Yes1 REST API with OAuth 2.0, webhooks, n8n node and Zapier Status: included, see footnote 1

E-invoicing

ZUGFeRD 2.x / Factur-X outgoing
Rechnungskit Yes ZUGFeRD 2.5 under EN 16931, every invoice Status: included
Fynn Yes1 every invoice, cancellation and credit note automatically as a ZUGFeRD PDF under EN 16931 (Fynn says ZUGFeRD 2.1), in all plans Status: included, see footnote 1
XRechnung for public-sector buyers
Rechnungskit Yes XRechnung 3.0 automatically as soon as the customer has a Leitweg-ID (public-sector routing ID) on file Status: included
Fynn Yes1 can be enabled per customer, with Leitweg-ID; sending via Peppol in private beta (Revenue Platform plan) Status: included, see footnote 1
Validation before sending
Mandatory fields under §14 UStG, tax rates, format rules
Rechnungskit Yes every invoice before sending (Mustang/EN 16931) Status: included
Fynn Not documented2 Fynn validates the DATEV export before handover; an EN 16931 check of every e-invoice before sending is not documented Status: no reliable source found, see footnote 2
Receive and process e-invoices
Rechnungskit No deliberately out of scope. Rechnungskit creates outgoing invoices Status: not available
Fynn Not documented1 Fynn only describes outgoing invoices Status: no reliable source found, see footnote 1

Shop automation

Own checkout link without a shop
One-time purchase and subscription: whose name, whose payment provider
Rechnungskit Yes, in your name checkout.rechnungskit.de/c/… for one-time purchases, /s/… per subscription plan; payment through your Mollie, Stripe, PayPal or Unzer account straight to your bank account, e-invoice right after payment Status: included
Fynn Yes, checkout link2 checkout link per product for one-time and recurring products, with discount codes, trial period and terms; payment runs through the payment methods connected in Fynn Status: included, see footnote 2
Native shop and payment integrations
no third-party tools
Rechnungskit Yes Shopify, WooCommerce and Shopware natively, Stripe/Mollie/PayPal/Unzer, own checkout link for one-time purchases and subscriptions without a shop, own push API Status: included
Fynn Payment methods, no shop1 Stripe (card), PayPal, GoCardless, own SEPA direct debit and EBICS, plus HubSpot, Salesforce and Attio; a connection to Shopify, WooCommerce or Shopware is not documented Status: limited, see footnote 1
Invoicing on the correct date of supply
shipping date instead of payment date, automatically
Rechnungskit Yes from the shop's shipping event; for subscriptions, the service period comes from the billing period Status: included
Fynn Period from the subscription2 revenue is booked to the right period based on the service period; a shipping event as the date of supply is not documented Status: limited, see footnote 2
Automatic cancellation invoices on refunds
including partial refunds
Rechnungskit Yes to the cent, with its own correction document Status: included
Fynn Yes, from Fynn2 a refund in Fynn creates the credit note and triggers the refund via Stripe or PayPal; cancellation only for unpaid invoices. The help center does not describe partial amounts separately Status: included, see footnote 2
Payout reconciliation with fees
Stripe, Mollie, PayPal and others as finished bookings
Rechnungskit Yes fees and payouts as bookings Status: included
Fynn Bank matching1 bank matching and matching of open items (from Quote-to-Cash); payment provider fees and payouts as separate bookings are not documented Status: limited, see footnote 1

Tax compliance

OSS / EU distance selling
Rechnungskit Yes destination-country rates, monitoring of the €10,000 threshold, export Status: included
Fynn Not documented2 website and help center do not mention an OSS procedure Status: no reliable source found, see footnote 2
EU tax rates updated automatically
Rechnungskit Yes monthly from the EU database TEDB, with change alerts Status: included
Fynn Not documented1 VAT and reverse charge are configured; automatic maintenance of EU tax rates is not documented Status: no reliable source found, see footnote 1
Qualified VAT ID (USt-IdNr.) check with evidence archive
Rechnungskit Yes qualified check with the BZSt (Federal Central Tax Office), response archived for 8 years Status: included
Fynn Not documented1 reverse charge is configurable; a VAT ID check with the BZSt or via VIES is not documented Status: no reliable source found, see footnote 1
Single- and multi-purpose vouchers (§3 (13) to (15) UStG)
Rechnungskit Yes own voucher and store-credit register Status: included
Fynn Not documented2 vouchers at Fynn are discount codes; single- and multi-purpose vouchers under § 3 (13) to (15) UStG are not mentioned Status: no reliable source found, see footnote 2
Deferred revenue (pRAP) / revenue recognition for subscriptions
Rechnungskit Yes pRAP for subscriptions and annual licenses Status: included
Fynn Yes, a strength2 pRAP under HGB automatically: created from the net amount, released monthly, reversed on cancellation, month-end close; the bookings are part of the DATEV export Status: included, see footnote 2

DATEV & archive

Finished DATEV booking records
not just document images
Rechnungskit Yes EXTF for SKR03/SKR04, revenue + payments + fees; document images via Beleglink in the "Belegtransfer" package for Unternehmen online Status: included
Fynn Yes2 booking batches, debtor master data and document images for SKR03 and SKR04, as a download or automatically via DATEVconnect online Status: included, see footnote 2
GoBD archive with locking (Festschreibung)
Rechnungskit Yes WORM archive, SHA-256, locked from creation Status: included
Fynn Provider's claim1 archiving "unchangeable, audit-proof" on servers in Germany according to Fynn, locking on DATEV export, locked month-end closes; an audit certificate is not mentioned in the sources checked Status: limited, see footnote 1
Free access for your tax advisor
Rechnungskit Yes own tax advisor portal, documents read-only Status: included
Fynn Tax advisor portal2 own access with documents and DATEV reports, enabled per organization via support; Fynn doesn't say whether it costs extra Status: included, see footnote 2

Accounting & operations

VAT return (UStVA) / cash-basis accounts (EÜR) / direct ELSTER filing
EC Sales List (ZM) import files are covered separately
Rechnungskit ZM data ZM import file yes; UStVA, EÜR and direct ELSTER filing stay with your tax advisor Status: limited
Fynn No1 by its own description not accounting software, Fynn "does not replace accounting"; UStVA and EÜR stay with your tax advisor, same as Rechnungskit Status: not available, see footnote 1
Entry price
Rechnungskit from €9 base fee + tiered price per document; free to test in sandbox mode Status: included
Fynn from €149/month3 Billing €149 paid monthly, €129 paid annually, €100,000 revenue a month included, 0.9% above that; Quote-to-Cash €399, Revenue Platform €799; unlimited invoices Status: note, see footnote 3
API for your own systems
Rechnungskit Yes push API in every plan Status: included
Fynn Yes1 REST API with OAuth 2.0, webhooks, n8n node and Zapier Status: included, see footnote 1
Sources & footnotes
  1. 1. Fynn website, checked on October 2, 2026: E-Rechnung, DATEV-Anbindung, Revenue Recognition, Integrationen, Stripe integration ("Stripe only for credit card payments"), grounding page (by its own description neither accounting software nor a payment provider) and llms.txt.
  2. 2. Fynn help center, checked on October 2, 2026: e-Rechnung, DATEV-Export, Rechnungsabgrenzung, Monatsabschluss, Korrigieren, Steuerberater-Portal, Gutscheine & Rabatte, Checkout-Link, Kundenbereich and Stripe Payments.
  3. 3. fynn.eu/pricing and the machine-readable version fynn.eu/pricing.md, checked on October 2, 2026: Billing €149, Quote-to-Cash €399, Revenue Platform €799 a month (€129, €349 and €699 per month paid annually), each with €100,000 revenue per month included, 0.9% or 0.65% above that. No statement on net or gross. The Rechnungskit price comes from the pricing curve on rechnungskit.de/preise (€9.00 base fee + €59.00 usage for 500 documents).
  4. Information from the provider's website and help center, last checked on October 2, 2026.
  5. Rows marked "Not documented" mean we found no reliable public source, not that the feature is missing.
  6. Rechnungskit information reflects the current product; items marked "Planned" are not available yet.
  7. Legal basis for the rows and sections (German law): mandatory invoice details § 14 (4) UStG, e-invoicing § 14 (1) and (2) UStG with the transition rules in § 27 (38) UStG, small-amount invoices § 33 UStDV, vouchers § 3 (13) to (15) UStG, OSS threshold § 3c (4) UStG and filing § 18j UStG, VAT ID confirmation § 18e UStG, intra-EU supply § 6a UStG, tax arising in the filing period of the supply § 13 (1) no. 1 (a) UStG, retention § 14b (1) UStG and § 147 (3) AO, deferred revenue § 250 (2) HGB, archive GoBD, BMF letter of 28.11.2019.

All information from publicly available sources, checked October 2, 2026. Providers' features and prices can change. Please report mistakes to support@rechnungskit.de. How we rate is explained in How we compare.

When is Fynn the better choice?

Rechnungskit doesn't do everything. In these cases, Fynn is the more honest recommendation.

You bill on usage or a hybrid model

Metering, billing by tokens or credits, tiers and base-price-plus-overage models are Fynn's core, in the Revenue Platform plan. Rechnungskit runs monthly and annual subscriptions with quantity, trial period and add-ons; there is no usage-based billing.

Your sales team works with quotes and a CRM

Fynn turns a deal in HubSpot or Salesforce into a quote with approval and e-signature and then creates the contract, with commission for the sales team if you like. Rechnungskit covers none of that.

You need dunning and collection through your house bank

Fynn sends dunning letters in several stages with fees, handles returned direct debits, hands open receivables to debt collection and collects SEPA business direct debits via EBICS directly at your bank. For pay-by-invoice, Rechnungskit sends two payment reminders and collects subscriptions via Mollie or Stripe.

You steer by MRR, churn and cohorts

Fynn calculates these metrics continuously from the billing data. Rechnungskit doesn't offer reports like that.

What Rechnungskit does differently

Tax compliance

VAT ID check with evidence archive

Qualified check with the BZSt (Federal Central Tax Office) including company name, city, postcode and street. The response is archived unchanged for eight years and linked to the individual invoice.

Qualified BZSt check instead of a simple format check
Response linked to the invoice and delivery date
No tax-exempt invoice without a usable check
Accounting

Payouts as finished bookings

Stripe, Mollie and PayPal don't pay out each payment individually but in lump sums with the fees already deducted. Rechnungskit breaks every payout down into payments, refunds and fees and passes them to your tax advisor as EXTF bookings, each invoice booking with a Beleglink to the e-invoice.

Payouts broken down into payments, refunds and fees
Fees booked separately from revenue
EXTF bookings for SKR03 and SKR04 with Beleglink
Your tax advisor downloads them directly

Price comparison

List prices net per month, as of October 2, 2026. Discounts and promotions are not included.

Rechnungskit List price
from €9 / month net + tiered price per document
Free to test in sandbox mode; billing starts at go-live
After that, a €9 base fee plus €0.15 to €0.03 per document
OSS, ZM, DATEV, GoBD archive and every feature always included
Self-service signup with no waiting list, up and running in minutes
Cancel monthly, no setup fee
Fynn Packages by feature
€149 to €799 / month, €100,000 revenue included, 0.9% or 0.65% above that
Billing €149 (€129 annually): subscriptions, GoBD invoices, e-invoicing, DATEV export, pRAP, customer portal
Quote-to-Cash €399 (€349 annually): adds quotes, dunning, bank matching, HubSpot
Revenue Platform €799 (€699 annually): adds usage-based billing, entitlements, multi-currency, Peppol (private beta)
Unlimited invoices and customers; above €100,000 revenue a month 0.9% (Billing) or 0.65%
14-day free trial, cancel monthly; startup program with 12 free months
Source: fynn.eu/pricing, as of October 2, 2026; the page doesn't say whether prices are net or gross
Worked example
SaaS with 500 subscription invoices and €25,000 subscription revenue a month: at Rechnungskit that is a €9.00 base fee plus €59.00 for 500 documents, including e-invoicing, GoBD archive, DATEV bookings and subscription billing via subscription links. At Fynn, the Billing plan at €149 a month (€129 paid annually) is enough, because €25,000 is below the included €100,000 in revenue. Dunning and bank matching only come with Quote-to-Cash at €399. Payment fees come on top in both cases.
Rechnungskit
€68.00
Fynn
€149

Switching in three steps

1
Set up plans

Create monthly and annual plans as subscription products in Rechnungskit and connect Mollie or Stripe. Each plan gets a subscription link, and the customer portal for cancellation and withdrawal is included.

2
Check in test mode

In test mode you sign up for a subscription yourself and check the invoice, number sequence and DATEV export. Only then do you go live.

3
Route new sign-ups

New customers sign up via the subscription link. Running Fynn contracts can't be taken over automatically; they continue there until they end. The old invoices stay in Fynn as records.

FAQ

Partly. For simple monthly and annual subscriptions, Rechnungskit can take over the billing itself: one subscription link per plan, collection via Mollie or Stripe by card or SEPA direct debit, a customer portal for cancellation and withdrawal, plus e-invoicing, GoBD archive and DATEV bookings. Rechnungskit doesn't have quotes and contract approvals, usage-based billing, dunning, CRM sync, commissions or SaaS metrics. If you depend on those, stay with Fynn.

Yes, but not for the same sales, because one sale gets exactly one invoice. A second invoice with VAT shown for the same revenue can trigger the VAT a second time with business customers (§ 14c (1) UStG). Rechnungskit creates invoices from the payments of a connected Stripe, Mollie or PayPal account. If Fynn collects through the same Stripe or PayPal account, one sale would end up with two invoices and two numbers. So keep the areas cleanly separated, for example Fynn with its own payment account for B2B contracts and Rechnungskit for shop and checkout sales. Before switching, try Rechnungskit in test mode; it only creates test documents and nothing is sent.

They stay where they are. Rechnungskit doesn't import or archive invoices created elsewhere; you keep meeting your retention duty for old documents (eight years under § 14b (1) UStG and § 147 (3) AO) in your previous system. What Rechnungskit can pull in are past orders and payments from your connected shops and payment providers, which then become new, validated invoices. For the number sequence, you set the number Rechnungskit continues from, so nothing overlaps with your old documents.

Documents are stored tamper-proof and unchangeable for eight years for as long as your account exists (WORM archive with checksums). Eight years is the retention period for invoices and accounting records (§ 14b (1) UStG, § 147 (3) AO); the requirements for the archive are set out in the GoBD. You can export them at any time, and for 90 days free of charge after you cancel. The final assessment of your process documentation (Verfahrensdokumentation) is up to your tax advisor.

Fynn is a billing platform from Fynn GmbH in Cologne for B2B SaaS companies in the DACH region. It bundles quotes (CPQ), subscription and usage-based billing, e-invoicing, SEPA collection, dunning, deferred revenue under HGB and the DATEV export. Fynn names companies with 10 to 500 employees and €500,000 to €50 million in annual recurring revenue as its target group. Stripe or PayPal are only payment methods there; subscriptions and invoices run in Fynn.

When billing itself is the problem, not just the document: contracts from quotes with approval and e-signature, billing by usage or tokens, dunning stages up to handing over to debt collection, business direct debit through your house bank or commissions for the sales team. Rechnungskit offers none of that. But if your customers buy through a shop, a checkout link or an existing Stripe setup and you need e-invoicing, archive and DATEV bookings from that, Rechnungskit is the smaller step.

Both. Fynn creates deferred revenue items from the net amount, releases them monthly, reverses them automatically on cancellation and includes them in the DATEV export. Rechnungskit also books pRAP in the DATEV export: the deferral in the invoice month and the release in the following months, net, spread by the method you choose: monthly (default), 30/360 or to the day. This requires that you prepare balance sheets and that the pRAP account is set in the DATEV settings. With cash-basis accounting (EÜR) there is no deferral.

Rechnungskit has a guided takeover for this. Subscriptions move at the end of their period with the existing payment mandate, and your customers don't have to do anything. Subscriptions with several line items or usage-based prices can't be taken over. On its comparison page, Fynn mentions a structured migration process. According to the Fynn help center, the documented Stripe migration assistant transfers stored credit cards; it doesn't migrate customers, products or subscriptions, which are created in Fynn.

From the providers' publicly available sources, checked on October 2, 2026, with footnotes for each row. Where we found no reliable source, the table says "Not documented". If you spot a mistake, write to support@rechnungskit.de and we'll correct it and re-date the page.

Related reading

More comparisons

Rechnungskit is not a tax advisory or law firm. This article explains general principles and does not replace advice from a tax advisor (Steuerberater, § 5 StBerG) or a lawyer (§ 3 RDG). Rechnungskit is built for businesses based in Germany and prepares documents, tax rates and bookings automatically. How your specific case is treated remains your decision, ideally together with your tax advisor or a lawyer.

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