Reg T versus portfolio margin
Post the same OCC cash and options book twice. Use account_type: REGT for strategy-based Reg T and account_type: C for TIMS portfolio margin.
common = {"exchange_code": "OCC", "contract_code": "AAPL"}
positions = [
{**common, "account_code": "REG_T", "account_type": "REGT", "contract_type": "CASH", "net_position": 100},
{**common, "account_code": "TIMS", "account_type": "C", "contract_type": "CASH", "net_position": 100},
]
results = requests.post(
f"{C9_API_ENDPOINT}/portfolios",
headers=HEADERS,
json={"calculation_type": "margins", "portfolio": positions},
).json()
Include identical option legs under both account codes, then compare each account's initial_margin. Reg T recognises fixed strategies. TIMS reprices the related portfolio through risk scenarios and applies eligible offsets.
Reg T initial margin: $26,350.91
TIMS portfolio margin: $6,638.13
TIMS minus Reg T: -$19,712.78
Portfolio margin applies only to an eligible, approved portfolio-margin account. Broker house requirements may exceed exchange or regulatory minimums.