Start by deciding which system is the source for each kind of record.
To connect a CRM and an accounting system, first decide which one is the source of truth for each type of record, then map how customers, products, and tax details match between them, and finally automate a small number of flows, such as a won deal creating an invoice and a recorded payment updating the customer in the CRM.
The first decision prevents most of the trouble later. Customers are often created in the CRM by sales, but their billing address, tax status, and payment terms belong to finance. Products and prices may live in accounting or an ERP. Invoices, payments, and credit memos should be created in accounting, with the CRM receiving a read-only copy.
Write these choices down as a short table: each record type, the system that holds the master version, which fields each side may change, and what happens when both change at once. Without that table, a two-way sync quietly overwrites good data with bad, and nobody can say which system is right when the numbers disagree.
Map customers, products, and tax details before moving any data.
Most CRMs and accounting systems describe the same customer differently. The CRM may hold a company with several contacts and deals, while accounting holds a customer with a billing contact, a currency, and a tax code. Parent companies, subsidiaries, and separate billing entities make this harder. Decide how each CRM account maps to one or more accounting customers.
Use a stable identifier to link the two records, usually the accounting customer ID stored on the CRM account, instead of matching by name or email. Names change and get misspelled, and email addresses belong to people who leave. The same principle applies to products, price books, and tax codes, which should be linked by code rather than by description.
Before the first sync, clean up duplicates on both sides and agree on required fields. An invoice cannot be created without a billing address, tax treatment, and terms, so the CRM needs to capture those when a deal closes or the flow will stop. Running the mapping against a copy of real records exposes the gaps early.
Choose the direction and trigger for each flow.
Keep the first set of flows small and one-directional where possible. A common starting point is that a deal marked won in the CRM creates or updates the customer in accounting and drafts an invoice or sales order. Finance then reviews and sends it, so a mistake entered in the CRM never reaches a customer automatically.
The return flow gives sales and account managers the financial context they usually ask finance for: invoice status, payments received, overdue balances, and credit holds. This data should appear in the CRM as read-only fields or a summary panel. Letting sales edit financial fields in the CRM and pushing those edits back is where many integrations go wrong.
For each flow, name the trigger, the fields that move, how often it runs, and what should happen when a record is updated or deleted after the first sync. Subscriptions, deposits, partial payments, refunds, and multi-currency deals each need an explicit rule. Listing them early avoids an integration that works in the demo and fails at month end.
Choose between a native connector, an integration platform, and custom code.
Many CRM and accounting products offer a native connector or a marketplace app. These are the simplest route when your process matches the connector’s assumptions: one company, one currency, standard products, and invoices created from closed deals. Check what it syncs, in which direction, how it handles conflicts, and whether it logs failures somewhere your team will see them.
Integration platforms, sometimes called iPaaS, sit between the two systems and let you build flows with more control over mapping and logic. They suit companies with several flows and someone able to maintain them. Watch for pricing that rises with task volume, and for flows that grow so complex that only the person who built them understands the rules.
Custom integration code, usually a small service using both systems’ APIs, fits when rules are unusual, volumes are high, several entities or currencies are involved, or the sync is critical enough to need testing, version control, and detailed error handling. It takes more effort to start but gives full control over behavior, logging, and how failures are retried.
Plan for errors, reconciliation, and the people who fix them.
Every CRM and accounting connection will eventually fail on a record: a missing tax code, a closed period, an expired credential, or a customer merged on one side only. Decide who is told, where they see the failed record, and how they correct and retry it. An integration without a visible error queue fails silently until month end.
Add a simple reconciliation check. Compare counts and totals of won deals, invoices, and payments between the systems on a regular schedule, and list anything that exists on one side and not the other. This turns disagreement into a short list someone can work through instead of a surprise during a close or an audit.
Finally, record the design: the source of each record, the field mapping, the flows and their triggers, and the error process. That document lets finance, sales operations, and any future developer change the connection safely. Baybloom builds CRM and accounting integrations, and the same document is the starting point whether the answer is a connector or custom code.
Put it into practice
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