Section 121 Non-Qualified Use 2009 Allocation 2026 Calculator

§121 non-qualified use 2009 rule allocates gain between qualifying primary residence periods and non-qualifying rental or second-home periods after January 1, 2009. Only the qualifying portion qualifies for the $250K/$500K home sale exclusion; depreciation recapture is always taxed separately at up to 25%.

How the Non-Qualified Use Rule Works

Enacted by the Housing and Economic Recovery Act of 2008 and effective January 1, 2009, IRC §121(b)(5) limits the exclusion when a residence was used for non-qualified purposes (rental, vacation home, business use other than home office in same dwelling) after that date. The allocation formula is: non-qualified gain = total gain × (non-qualified use period after 2009 / total ownership period). The non-qualified portion never qualifies for exclusion. The qualifying portion is then subject to the standard $250K (single) or $500K (married filing jointly) cap.

What Counts as Non-Qualified Use

Per Treas. Reg. §1.121-1(b)(5): rental periods (residential or short-term), use as a vacation or second home, and business use outside the dwelling unit. Excluded from non-qualified use: (1) periods after the home was last used as primary residence but before sale (within 5 years), (2) temporary absences for health, employment change, or unforeseen circumstances under §121(d)(11), and (3) any period before January 1, 2009 (grandfathered). Depreciation taken on a home office or rental conversion is always recaptured at up to 25% under §1250, regardless of allocation.

Worked Example: $300K Gain, 4 Years Rental

Couple owns home 15 years (180 months), rented it out 4 years (48 months) post-2009 before selling. NQU ratio = 48/180 = 26.67%. Of $300K gain, $80K is non-qualified (taxable LTCG), $220K is qualifying — fully covered by $500K MFJ exclusion. If $20K depreciation was claimed during the rental, $20K is recaptured at 25% ($5,000 tax) before the §121 allocation. Net: $80K × 15% LTCG = $12,000 + $5,000 recapture = $17,000 federal tax. Without §121(b)(5), entire $300K would have been excluded.

Common Mistakes to Avoid

(1) Forgetting depreciation recapture is separate — §1250 recapture comes off the top before allocation. (2) Counting pre-2009 rental periods — those are grandfathered and ignored. (3) Counting post-residence rental as NQU — periods after the home stopped being primary residence but within the 5-year ownership/use test window are not non-qualified use. (4) Misclassifying second home as NQU when never rented — second home use IS non-qualified per §121(b)(5)(C)(ii). (5) Ignoring state tax — California, New York, and others tax the full gain regardless of federal exclusion.

Last updated May 2026. Sources: IRC §121(b)(5), Treas. Reg. §1.121-1, IRS Pub 523. Estimates only — consult a CPA.