Under the home sale exclusion rules, you can use part of the exclusion if you cannot meet the two-year test for owning and living in the home under certain conditions. The failure to meet the test must be the result of a change in employment, health, or unforeseen circumstances. If you fall within this safe harbor, then the exclusion is limited to the portion of the two-year period that was satisfied. The allocation is based on the exact number of days of ownership and use of the home as a principal residence.
For calendar year 2007, taxpayers covered by an HDHP may contribute up to the lesser of the annual deductible or $2,850 ($5,650 for family coverage).