Example (1). In 1940, H purchased real property for $15,000 which he caused to be transferred to himself and W (his wife) as tenants by the entirety. In 1956 when the fair market value of the property was $30,000, W made $5,000 improvements to the property. In 1957 the property was sold for $35,000. The general appreciation of $15,000 which occurred between the date of purchase and the date of W's improvements to the property constitutes an additional contribution by H, having the same characteristics as his original contribution of $15,000.
Example (2). In 1955 real property was purchased by H and W and conveyed to them as tenants by the entirety. The purchase price of the property was $15,000 of which H contributed $10,000 and W, $5,000. In 1960 when the fair market value of the property is $21,000, W makes improvements thereto of $5,000. The property then is sold for $26,000. The appreciation in value of $6,000 results in an additional contribution of $4,000 (10,000/15,000 * $6,000) by H, and an additional contribution by W of $2,000 (5,000/15,000 * $6,000). H's total contribution to the tenancy is $14,000 ($10,000 + $4,000) and W's total contribution is $12,000 ($5,000 + $2,000 + $5,000).
Example (3). In 1956 real property was purchased by H and W and conveyed to them as tenants by the entirety. The purchase price of the property was $15,000, on which a down payment of $3,000 was made. The remaining $12,000 was to be paid in monthly installments over a period of 15 years. H furnished $2,000 of the down payment and W, $1,000. H paid all the monthly installments. During the period 1956 to 1971 the property gradually appreciates in value to $24,000. Here, the appreciation is so gradual and the contributions so numerous that the amount allocable to any particular contribution cannot be ascertained with any reasonable certainty. Accordingly, in such a case the appreciation in value may be disregarded in determining the amount of consideration furnished in making the computations provided for in §§ 25.2515-3 and 25.2515-4 .
To the extent that all three of the conditions set forth in this subdivision are not met (whether by reason of the death of one of the spouses or for any other reason), the provisions of the preceding sentence shall not apply, and the sale, exchange or other disposition of the property will constitute a termination of the tenancy. As used in subdivision (c) the expression "a reasonable time" means the time which, under the particular facts in each case, is needed for those matters which are incident to the acquisition of the other property (i.e., perfecting of title, arranging for financing, construction, etc.). The fact that proceeds of a sale are deposited in the name of one tenant or of both tenants separately or jointly as a convenience does not constitute a division within the meaning of subdivision (a) if the other requirements of this subdivision are met. The proceeds of a sale, exchange, or other disposition of property held as tenants by the entirety will be deemed to have been used for the purchase of other real property if applied to the purchase or construction of improvements which themselves constitute real property and which are additions to other real property held by the spouses in a tenancy identical to that in which they held the property which was sold, exchanged, or otherwise disposed of.
26 C.F.R. §25.2515-1