Mortgage Reserves Requirement (Months PITI)
Required reserves (PITI x months) vs eligible liquid plus allowable retirement assets.
Example
You enter
- Monthly PITI ($) 2500
- Reserves required (months) 6
- Liquid assets after closing ($) 20000
- Vested retirement balance ($, optional) 30000
- Retirement allowable (percent; Fannie Mae 100) 60
You get
- Required reserves $15000
- Eligible assets 38000
- Delta 23000
Checked against published worked examples from: Fannie Mae Selling Guide B3-4.1-01 / B3-4.3-03 (public).
Details, formula, and sources
ScopeSurplus or shortfall and months of PITI covered.
Formula or tablerequired = PITI_monthly * reserves_months. eligible = liquid_assets + retirement_balance * retirement_allowable_pct/100. delta = eligible - required. months_covered = eligible / PITI_monthly.
Source and editionFannie Mae Single-Family Selling Guide B3-4.1-01 (reserves) and B3-4.3-03 (retirement-account funds). Freddie Mac Single-Family Seller/Servicer Guide 5501.2.
Free accessFannie Mae Selling Guide free at selling-guide.fanniemae.com; Freddie Mac Guide free at guide.freddiemac.com.
What governsEstimate. Lender governs final underwriting and rate / fee disclosure. Appraiser governs the appraised value. State law and the agency's program guidelines may impose stricter limits than the published thresholds.
API field namespiti_monthly, reserves_months, liquid_assets, retirement_balance, retirement_allowable_pct, required, eligible, delta
- Reserve unit one month of full PITIA paymentFannie Mae B3-4.1-01
- Retirement allowance default 100% of the vested balance (no discount in Fannie Mae B3-4.3-03), user-adjustable for a program that discountsFannie Mae B3-4.3-03