Microsoft Dynamics 365 Business Central and PayPal integration

What moves between them

Money out flows from Microsoft Dynamics 365 Business Central to PayPal. ml-connector reads open or posted purchase invoices and their vendor records, then creates PayPal payout batch items addressed to each vendor's PayPal email for the invoice amount and currency. Money in and reconciliation flow from PayPal to Business Central. ml-connector reads PayPal captures and settled transactions and writes them as customer payment journal lines, applied to the matching sales invoice. Payout and capture webhooks trigger the work as it settles, while a scheduled transaction search poll in 31-day windows backfills anything a webhook missed.

How ml-connector handles it

ml-connector stores both credential sets encrypted, mints a Business Central token from Microsoft Entra ID, and exchanges PayPal client credentials for a bearer token that it caches for the full lifetime rather than per call. The link between the two systems is the PayPal invoice_id field: ml-connector writes the Business Central invoice number into invoice_id on each payout and reads it back on captures and transactions to apply payments to the right document. Because PayPal payouts target an email address and have no supplier registry, each vendor must carry a PayPal email, and payouts to a recipient with no PayPal account stay unclaimed. Every payout sends a PayPal-Request-Id and a stable sender_batch_id so a retried send never pays a vendor twice, matching Business Central best practice of filtering by invoice number before posting. PayPal returns HTTP 429 under dynamic throttling and publishes no fixed limit, so the connector backs off with jitter; the 31-day search window and the up-to-3-hour settlement delay are handled by a windowed backfill loop. PayPal webhook signatures are verified with the RSA-SHA256 certificate from the validated paypal.com cert URL, and Business Central subscriptions are renewed before the 3-day expiry. Every record carries a full audit trail and can be replayed if a downstream call fails.

A real-world example

A 90-person online education company runs Microsoft Dynamics 365 Business Central for finance and bills a roster of remote contractors and small overseas suppliers who all prefer PayPal. Before the integration, accounts payable exported approved bills from Business Central, logged into PayPal to send each payout by hand, then downloaded the monthly PayPal activity report and keyed payments back against invoices one by one, which left settled fees and refunds unreconciled for weeks. With Business Central and PayPal connected, approved purchase invoices go out as PayPal payouts automatically, and settled captures and transactions post back as customer payments tagged to the originating invoice. The contractor payment run drops from a full afternoon to a review step, and the PayPal clearing account reconciles itself.

What you can do

• •Pay approved Business Central purchase invoices as PayPal payouts to each vendor's PayPal email.
• •Post settled PayPal captures and transactions back into Business Central as customer payment journal lines.
• •Apply payments to the right document by carrying the Business Central invoice number in the PayPal invoice_id field.
• •Bridge Microsoft Entra ID client credentials on Business Central and OAuth bearer tokens on PayPal, caching each token for its full lifetime.
• •Poll PayPal transaction search in 31-day windows and verify RSA-SHA256 webhooks, with retries and a full audit trail on every record.

Questions

Which direction does data move between Microsoft Dynamics 365 Business Central and PayPal?

Money out flows from Business Central to PayPal as payouts created from approved purchase invoices. Money in flows from PayPal to Business Central, where settled captures and transactions are posted as customer payment journal lines. PayPal is treated as a payments source, so the connector reads its activity for reconciliation rather than writing ledger entries into PayPal, which has no GL.

How are PayPal payments matched to the right Business Central invoice?

ml-connector writes the Business Central invoice number into PayPal's invoice_id field when it creates a payout, then reads that same invoice_id back on captures and transaction search results to apply each payment to the matching document. Because invoice_id is a free-text reference, the connector populates it consistently on every send. This keeps the PayPal clearing account aligned with the ledger.

How does the integration deal with PayPal's transaction search limits and settlement delay?

PayPal transaction search is read-only and capped at a 31-day window per request, and settled transactions can take up to 3 hours to appear, so ml-connector runs a windowed backfill loop across multiple 31-day ranges and reconciles on a schedule. Payout and capture webhooks trigger posting as soon as activity settles, and the poll backfills anything a webhook missed. PayPal does not publish fixed rate limits, so the connector caches its bearer token and backs off on HTTP 429.