LawDiver for Tax API
Dedicated endpoints — not a flag on caselaw search. Create a regular LawDiver account, mint an ld_tax_ key, and call /api/v1/tax/*.
Send your Tax key as Authorization: Bearer ld_tax_…, X-API-Key, or lawdiver_api_key. Caselaw ld_live_ keys are rejected on this surface. The free web product at /tax needs no key.
Same accounts as the rest of LawDiver.
Account → API Keys → Tax API (prefix ld_tax_).
Base URL https://lawdiver.com. See endpoints below and github.com/lawdiver/LawDiver-tax-api.
All methods are POST with a JSON body. Responses use the standard LawDiver /api/v1 envelope.
POST /api/v1/tax/search — Query across IRC, Treas. regs, IRS guidance, written determinations, forms/pubs, treaties, and IRM.
POST /api/v1/tax/law — Fetch a Code or regulation section as of a year, optionally redline against another year.
POST /api/v1/tax/guidance — Resolve a Rev. Rul., Rev. Proc., notice, PLR, or other guidance cite with status and optional cited-by.
POST /api/v1/tax/check — Verify up to 50 tax authority cites in one call — existence, adverse status, judicial notes.
POST /api/v1/tax/case-context — IRS authorities tied to a Tax Court or other opinion id.
POST /api/v1/tax/treaty — U.S. income-tax treaty articles by country, topic, or article, as of a date.
POST /api/v1/tax/form — IRS form or instruction revision by number and optional tax year.
POST /api/v1/tax/whats-new — Guidance and forms published since a date, optionally filtered by Code sections.
Query across IRC, Treas. regs, IRS guidance, written determinations, forms/pubs, treaties, and IRM.
{
"query": "qualified business income",
"sources": ["irc", "guidance"],
"codeSection": "199A",
"limit": 10
}Fetch a Code or regulation section as of a year, optionally redline against another year.
{
"kind": "irc",
"cite": "163",
"asOf": 2018,
"compareTo": 2016,
"includeText": true
}Resolve a Rev. Rul., Rev. Proc., notice, PLR, or other guidance cite with status and optional cited-by.
{
"cite": "Rev. Rul. 99-7",
"includeText": true,
"includeCitedBy": true
}Verify up to 50 tax authority cites in one call — existence, adverse status, judicial notes.
{
"cites": ["I.R.C. § 61", "Treas. Reg. § 1.61-1", "Rev. Rul. 99-7"]
}IRS authorities tied to a Tax Court or other opinion id.
{
"opinionId": 12345678
}U.S. income-tax treaty articles by country, topic, or article, as of a date.
{
"country": "Germany",
"topic": "dividends",
"asOf": "2024-01-01"
}IRS form or instruction revision by number and optional tax year.
{
"number": "1065",
"part": "form",
"taxYear": 2024,
"includeText": true
}Guidance and forms published since a date, optionally filtered by Code sections.
{
"since": "2026-01-01",
"codeSections": ["163"],
"limit": 50
}curl -s https://lawdiver.com/api/v1/tax/law \
-H "Authorization: Bearer ld_tax_YOUR_KEY" \
-H "Content-Type: application/json" \
-d '{"kind":"irc","cite":"61","asOf":2024,"includeText":true}'const res = await fetch('https://lawdiver.com/api/v1/tax/guidance', {
method: 'POST',
headers: {
Authorization: `Bearer ${process.env.LAWDIVER_TAX_API_KEY}`,
'Content-Type': 'application/json',
},
body: JSON.stringify({ cite: 'Rev. Rul. 99-7', includeText: true }),
});
const json = await res.json();import os, requests
r = requests.post(
"https://lawdiver.com/api/v1/tax/check",
headers={"Authorization": f"Bearer {os.environ['LAWDIVER_TAX_API_KEY']}"},
json={"cites": ["I.R.C. § 61", "Rev. Rul. 99-7"]},
)
print(r.json())Integration starter and SEO-friendly docs: https://github.com/lawdiver/LawDiver-tax-api. Free web: LawDiver for Tax.