One source of truth
Eligibility, calculator, and audit all read the same table. No 'spreadsheet drift' between teams.
Capability · AMI & eligibility
AMI lookups and eligibility, on the same wire as pricing.
FFIEC-aligned area median income lookups by state + county FIPS, percent-of-AMI calculation with family-size adjustments, and eligibility integration with the pricing engine. One source of truth, one API surface, no spreadsheets.
Overview
What it is, in one paragraph
AMI areas are keyed by (stateCode, countyFips). The percent-of-AMI endpoint applies the FFIEC family-size adjustment factors and returns a precise percent value. The pricing engine consumes the same data via Stage 1 eligibility — when a program restricts to ≤80% AMI, the engine looks up the borrower's percent-of-AMI from the same table powering the API.
FFIEC-aligned tables
AMI tables are loaded by version + year and addressable by state + county FIPS. Family-size adjustment factors follow FFIEC formulas.
Pricing-integrated
Stage 1 eligibility uses the same AMI table the API returns. No reconciliation, no skew, no 'wait, which AMI was that?'
As-of queries
Every lookup can specify a year so historical replay against the right AMI table is one parameter away.
Bulk admin
Admin endpoints for paginated area listing and detail. Useful for downstream BI tooling.
Public lookup
Anonymous AMI lookups are available on the marketing-side calculator at /resources/calculators/ami — useful for sales conversations.
Family-size factor
Applies the FFIEC factor automatically; the response carries both the unadjusted median and the adjusted median for transparency.
How it works
The pipeline, end to end.
Numbered steps from input to output. Each step maps to a specific subsystem you can inspect via OpenTelemetry.
- 1
Provide state + county FIPS
FIPS codes are stable. The API resolves the area row from the active table for the requested year (default: current).
- 2
Apply family-size factor
FFIEC publishes household-size adjustment factors for 1-8 person households. The endpoint applies the factor and returns the adjusted median.
- 3
Compute percent
If annualIncome is supplied, the response includes the percent-of-AMI rounded to one decimal place.
- 4
Engine consumes the same view
Stage 1 eligibility queries the AMI service through the platform's internal client; the table version used is logged with the quote's correlationId.
- 5
Replay against historical year
Pass tableYear in the lookup or the as-of timestamp on a pricing replay; the engine pulls the AMI snapshot that was active then.
Hands on
AMI percent calculation
Live cURL sample — copy, paste, ship.
# Lookup AMI and percent-of-AMI in one call
curl 'https://api.ratestack.com/v1/ami/percent?\
stateCode=CA&countyFips=06037&familySize=4&annualIncome=98000' \
-H "X-API-Key: $RATESTACK_KEY"
# Returns the active AMI table with the calculation
{
"stateCode": "CA",
"countyFips": "06037",
"areaName": "Los Angeles County",
"familySize": 4,
"annualIncome": 98000,
"medianIncome": 95800,
"adjustedMedian": 95800,
"percentOfAmi": 102.3,
"tableYear": 2025
}Why this matters
The pain it removes.
Auditable replay
Disputes about a 2024-Q3 program eligibility check against AMI replay correctly because the year-tagged table is still queryable.
Sales accelerant
The public AMI calculator lives on the marketing site and turns into a perfect lead-in: 'See your borrower's percent-of-AMI in 5 seconds.'
Frequently asked
Direct answers, no marketing spin.
How often are AMI tables updated?
Annually with the FFIEC release. Each release lands as a new year-tagged table; historical years remain queryable indefinitely.
Can I import my own area definitions?
Not currently — RateStack uses FFIEC keying so federal and state programs reconcile. If you need custom geographies, contact us.
What about MSAs vs. counties?
FFIEC publishes both. We use county-level FIPS as the canonical key and resolve metro/non-metro derivations server-side.
Does this affect HMDA reporting?
Indirectly — the eligibility audit captures which AMI table version was used. You can replay any prior quote with the corresponding AMI snapshot for HMDA reconciliation.
Related capabilities
Pieces that work better together.
Ready to see it on your data?
Wire ami lookups and eligibility, on the same wire as pricing. up to your real workflow.
We'll spin you a sandbox, load your actual ratesheets, and walk you through this capability against your top scenarios.