Service status ·A8 Core™ · The Operating System for Financial Accounts ·The account operating system · API-first

A8Core™

API reference v1

Account types

Solo 401(k) — Traditional

I.R.C. § 401(a); trust per ERISA § 403(a); Title I exempt, 29 C.F.R. § 2510.3-3

On this pageOverview Authority Parameters Example Eligible assets Rules

Slug	`solo-401k-traditional`
Nature	`PlanHolding` — Assets held in trust under a plan. A named trustee is required.
Contributions	`Deductible`
Earnings	`TaxDeferred`
Contribution year	`PlanYear`
Status	ship
Legacy code	`SKT` — ISCP import and statement templates only. Not identity, and not accepted by the API.

Required authority

An institution may open this account only if it satisfies every requirement group below. Within a group, any one authority suffices. Across groups, all must be satisfied.

Group	Any one of
Group 1	`ErisaTrustee`
Group 2	`IrsNonbankCustodian` or `Bank` or `StateTrustCompany`

Resolve availability at runtime with GET https://api.a8core.io/v1/account-types. Never hard-code it.

Create Account parameters

POSThttps://api.a8core.io/v1/accountsoperation: CreateAccount

Name	Type		Description
ProviderReferenceId	string	optional	Your internal reference. Used as the idempotency key.
ClientId	Guid	required	The A8 Core™ Client ID that owns the account.
AccountTypeCode	string	required	Must be `solo-401k-traditional`.
InstitutionId	Guid	required	The institution holding the assets.
TrusteeId	Guid	required	ERISA § 403(a): plan assets must be held in trust by a named trustee. Non-nullable.
PlanId	Guid	required	The sponsoring plan.
InvestmentId	long	optional	Links the account to a sponsor investment.

Example

POST https://api.a8core.io/v1/accounts

"ProviderReferenceId": "acct-10293",
"ClientId": "8fa2c1e4-5b6d-4f3a-9c2e-7d1a2b3c4d5e",
"AccountTypeCode": "solo-401k-traditional",
"InstitutionId": "b4c1e770-9d33-4a02-91ef-2c6a8b5d0f14",
"TrusteeId": "1f0c9a44-7e21-4b38-b0d6-3a5c8e2f9011",
"PlanId": "6d2b7e10-4c88-4a91-9f23-8b1e0c7d5a44"

200 OK

"RequestId": 1736472901835,
"Status": 1,
"AccountId": "3c7b1f90-2a44-4e21-8d6c-9b0e5a1f7c22"

Errors

ErrorCode	Meaning
InstitutionNotAuthorizedForAccountType	The institution does not hold every authority this type requires.
ClientNotFound	No client matches the supplied ClientId.

Eligible assets

The row below is the account-type dimension only. What this account may actually hold is the intersection of the account-type rule, the asset-class rule, any instrument predicates, and the institution’s authority asset scope.

●Permitted◐Conditional○Not permitted

Account family	Stocks & ETFs	Mutual funds	Bonds & fixed income	Cash & money market	Real estate	Private equity & venture	Private credit & notes	Precious metals	Digital assets	Stablecoins
Solo 401(k)	Permitted	Permitted	Permitted	Permitted	Conditional	Conditional	Conditional	Conditional	Conditional	Conditional

Plan document governs; trustee directs

Rules that govern this type

Title I exempt where there are no common-law employees (29 C.F.R. § 2510.3-3), but a trust is still required under I.R.C. § 401(a).
TrusteeId is non-nullable. A plan account without a trustee cannot lawfully exist.