What is the boundary of one set of books? A Xero tenant and a QuickBooks realm are each one company, full stop. A NetSuite account holds a subsidiary tree with elimination and consolidated rates built in. A group spanning both is the normal case, and only one of them will help you.
Xero
GET /connections, GET /Organisation
One organisation per tenant id
QBO
GET /companyinfo/{realmId}
One company per realm
NetSuite
SuiteQL: FROM subsidiary
A hierarchy inside one account
Read across a row. Where a cell is absent, the concept has nowhere to live in that system — which is a design constraint, not a gap to paper over.
A difference stated without a response is trivia. Each of these carries the handling.
Ids are unique per entity type within a realm. Invoice 145 and Bill 145 are different documents. Any cache key, URL or React key built from the id alone will collide, and the collision looks like data corruption rather than a key bug.
Do — Key everything as {system}:{tenantId}:{entityType}:{id}. Make the canonical id a branded string so a bare source id cannot be assigned to it.
A group on Xero or QBO is n disconnected tenants. You own the entity tree, the intercompany elimination and the currency translation. On NetSuite all three exist already, and ignoring them produces double-counted intercompany revenue.
Do — Own the entity tree in your schema. Map NetSuite subsidiaries into it rather than adopting them as the tree, so a mixed group — two Xero orgs plus a NetSuite subsidiary, which is common — still has a coherent parent.
The same access token serves every connected organisation; the Xero-Tenant-Id header decides which one you are talking to. A misthreaded header writes an invoice into the wrong company's books, and the API cannot tell you that you meant otherwise.
Do — Never carry the tenant id in ambient context. Pass it explicitly through every adapter call, and assert it against the record's expected tenant before any write.
/** Branded, so a bare source id cannot be passed where a canonical one belongs. */
type LedgerId = string & { readonly __ledgerId: unique symbol };
const ledgerId = (s: SourceRef): LedgerId =>
`${s.system}:${s.tenantId}:${s.entityType}:${s.id}` as LedgerId;
type Entity = {
id: string;
name: string;
parentId?: string; // our tree, not the source's
baseCurrency: string;
/** How this entity's books are reached. One entity, one connection. */
connection: { system: SystemId; tenantId: string; subsidiaryId?: string };
eliminates?: boolean; // NetSuite elimination subsidiary
};The payoff. Every difference above that reaches the surface, and what the component does about it.
The normalised object above is what the components read. These are the surfaces it feeds, the words for the concepts in it, and the document that explains the accounting.
Compared acrossXero docsQuickBooks Online docsNetSuite docs