Deltek and Plaid integration

What moves between them

The primary flow runs from Plaid into Deltek. ml-connector pulls cleared bank transactions and current balances from Plaid and posts them into Deltek so deposits reconcile against AR cash receipts and outgoing payments reconcile against AP vendor payments, leaving the Deltek ledger as the system of record. Where ACH payment initiation is enabled, the flow also runs the other way: an approved Deltek vendor payment is submitted through Plaid Transfer, and the transfer status is written back to Deltek as a payment record once it settles. Plaid has no invoices, vendors, or GL accounts to receive, so reference data and accounting entries stay in Deltek.

How ml-connector handles it

ml-connector stores both credential sets encrypted. On the Deltek side it accepts the full tenant URL per customer, requests an OAuth2 password-grant token, and refreshes it when a call returns 401. On the Plaid side it sends the client ID and secret on every POST and uses the per-user Item access token captured from Plaid Link, because bank connections cannot be bulk imported server-side. Transactions are read with the Plaid cursor sync, applying added, modified, and removed records in order, and a verified SYNC_UPDATES_AVAILABLE webhook triggers an early pull; because Deltek has no signed webhook, Deltek itself is reconciled on a schedule. Bank accounts are mapped to Deltek GL cash accounts first so every match lands on a valid account. For ACH initiation, ml-connector follows Plaid's authorize-then-create sequence, sends an idempotency key, truncates the ACH description to ten characters, and treats transfer status as event-driven through TRANSFER_EVENTS_UPDATE rather than polling. A 500 on transfer creation is verified against transfer events before any retry, since the transfer may already exist. Plaid 429 and shared institution rate limits are handled with exponential backoff, and every record carries a full audit trail and can be replayed if a downstream call fails.

A real-world example

A mid-sized architecture and engineering firm of about 250 staff runs Deltek Vantagepoint for project accounting, client billing, and the general ledger, and holds its operating and trust accounts at two banks. Before the integration, an accountant downloaded bank statements each morning and ticked them off by hand against the cash receipts and vendor payments recorded in Deltek, and unmatched items lingered until month-end. With Deltek and Plaid connected, cleared bank transactions flow in from Plaid daily and match automatically against the AR receipts and AP payments already in the ledger, so exceptions surface the same day instead of at close. When ACH initiation is enabled, approved vendor payments are sent through Plaid Transfer and the settled status posts straight back to the Deltek payment record.

What you can do

• •Pull cleared bank transactions and balances from Plaid and reconcile them against Deltek AR cash receipts and AP vendor payments.
• •Map Plaid bank accounts to Deltek GL cash accounts so every match lands on a valid account.
• •Initiate approved Deltek vendor payments through Plaid Transfer and write the settled status back as a Deltek payment record.
• •Bridge Deltek OAuth2 password-grant tokens on a tenant URL with Plaid client ID, secret, and a per-user Item access token from Plaid Link.
• •Read transactions through the Plaid cursor sync and reconcile Deltek on a schedule, since Deltek has no signed webhook.

Questions

Which direction does data move between Deltek and Plaid?

The main flow is Plaid into Deltek: cleared bank transactions and balances are read from Plaid and matched against AR cash receipts and AP vendor payments in Deltek. When ACH initiation is enabled, payments also flow the other way, with an approved Deltek vendor payment sent through Plaid Transfer and its settled status written back to Deltek. Plaid has no invoices, vendors, or GL accounts, so accounting entries stay in Deltek.

Can Plaid send invoices or purchase orders into Deltek?

No. Plaid is a bank-data network, not an ERP, and it has no invoice, purchase order, vendor, or GL account objects. What it provides is linked bank accounts, balances, bank-level transactions, ACH and routing numbers, and ACH or wire transfer initiation. ml-connector uses that bank activity to reconcile and pay against the invoices and payments that already live in Deltek.

How does the integration handle authentication and Deltek's lack of signed webhooks?

ml-connector requests a Deltek OAuth2 password-grant bearer token against the customer's tenant URL and refreshes it on a 401, while on the Plaid side it sends the client ID and secret on every POST and uses a per-user Item access token captured through Plaid Link. Plaid pushes JWT-signed webhooks that are verified before use, but Deltek webhooks carry no HMAC signature, so Deltek is reconciled by polling on the cadence you set.