Xero and Paychex integration

What moves between them

The main flow runs from Paychex into Xero. After each payroll period closes, ml-connector reads Paychex worker records and payroll transactions, then posts payroll accruals, expense allocations, and tax liability entries into Xero's general ledger as manual journal entries, mapped to the correct expense and liability accounts. Worker records also flow from Paychex into Xero's contact list so headcount and employment status in Xero reflect current Paychex data. This is a unidirectional flow; Xero is read-only and serves as the general ledger system of record.

How ml-connector handles it

ml-connector stores both OAuth2 credential sets encrypted and refreshes the Xero bearer token every 25 minutes before expiry, while Paychex tokens are re-acquired proactively on a similar cadence since no refresh token is issued. Xero requires the tenant organization ID in a header on every call, so ml-connector stores that per customer. Paychex webhook payloads contain only metadata, so ml-connector fetches the full record after each webhook arrives, then processes worker and payroll data on the schedule you define. Payroll accruals and distributions are posted into Xero as line-item manual journal entries, each debiting the appropriate expense or liability account and crediting the offsetting payable or cash account. Worker names, addresses, and employment status from Paychex are synced into Xero contact records, with the worker ID stored as a custom field for matching on future updates. Xero's rate limits of 60 calls per minute per tenant are observed, so ml-connector queues batch operations and backs off on 429 responses. Every record carries an audit trail and can be replayed if a downstream call fails.

A real-world example

A growing professional services firm uses Xero for accounting and Paychex Flex for payroll across three offices and about 80 employees. Before the integration, the finance team ran payroll in Paychex, then manually downloaded a payroll register each period and posted the expense and liability accruals into Xero by hand, taking several hours per month-end close and creating the risk of transposition errors. With Xero and Paychex connected, each payroll close automatically posts the accruals and distributions into Xero, mapped to the correct GL accounts. The finance team now opens Xero to find the payroll entries already there, correctly allocated, with no manual re-entry step. New hires and terminations that the HR team enters in Paychex immediately update the Xero contact list, keeping the headcount report in Xero in sync with actual staffing.

What you can do

• •Post payroll accruals and distributions from Paychex into Xero's general ledger as manual journal entries after each pay period.
• •Keep Xero contact records synchronized with Paychex worker data including names, addresses, and employment status.
• •Map payroll expense and liability accounts in Xero correctly to match your accounting structure.
• •Authenticate Paychex with Client Credentials flow and Xero with OAuth2 Authorization Code flow, managing token refresh for both.
• •Sync on a schedule tied to your payroll calendar, with retries on rate-limit backoff and a full audit trail on every entry.

Questions

What payroll data flows from Paychex into Xero?

After each payroll period, ml-connector reads Paychex payroll components, employee allocations, and pay distributions, then posts the expense accruals and tax liability entries into Xero as manual journal line items. Worker records also sync to keep Xero contacts current with Paychex hires, terminations, and updates. GL postings flow one direction only; Xero serves as the system of record and Paychex payroll data is read-only.

How does ml-connector handle the different OAuth2 flows between Xero and Paychex?

Xero uses Authorization Code flow with user consent and issues both access and refresh tokens, while Paychex uses Client Credentials with no refresh tokens. ml-connector stores both credential sets encrypted, refreshes the Xero token every 25 minutes, and re-acquires the Paychex token proactively on the same cadence to avoid expiry mid-sync.

Does the integration respect Xero's API rate limits?

Yes. Xero enforces a limit of 60 calls per minute per tenant and 5000 per day. ml-connector queues batch operations within those limits and backs off on HTTP 429 responses, retrying with exponential jitter. Payroll syncs are scheduled during low-traffic windows to reduce contention.