R.C. 5711.02 requires all taxpayers to file a return annually listing all taxable property. R.C. 5711.16 directs manufacturers and refiners on listing personal property and inventory:

“A person who purchases, receives, or holds personal property for the purpose of adding to its value by manufacturing, refining, rectifying, or combining different materials with a view of making a gain or profit by so doing is a manufacturer. When such person is required to return a statement of the amount of his personal property used in business, he shall include the average value, estimated as provided in this section, of all articles purchased, received, or otherwise held for the purpose of being used, in whole or in part, in manufacturing, combining, rectifying, or refining, and of all articles which were at any time by him manufactured or changed in any way, either by combining, rectifying, refining, or adding thereto, which he has had on hand during the year ending on the day such property is listed for taxation annually, or the part of such year during which he was engaged in business. * * * ”

Ashland argues that the present-worth method it presented to the BTA to value this disputed inventory, i.e., the safety-zone oil and bottom oil, established the value of the inventory. The commissioner contends that this method was flawed. We agree with the commissioner.

When a taxpayer challenges the commissioner’s determination of value by appealing to the BTA, the taxpayer “ * * * has the burden to prove that the commissioner’s valuation does not accurately reflect true value.” Snider v. Limbach (1989), 44 Ohio St.3d 200, 201, 542 N.E.2d 647, 649. The taxpayer must present competent and probative evidence to show that the commissioner’s determination of value is factually incorrect. Hatchadorian v. Lindley (1986), 21 *80Ohio St.3d 66, 21 OBR 365, 488 N.E.2d 145, paragraph two of the syllabus. The commissioner may also value property according to pre-determined formulae to ascertain value, but the commissioner must adjust the formulae “when special or unusual circumstances or conditions of use exist or when evidence shows that rigid application would be inappropriate.” Snider v. Limbach, supra, 44 Ohio St.3d at 201, 542 N.E.2d at 649.

First, whether Ashland can identify a specific inventory of oil to be valued under its approach is unimportant in this case. Oil is a fungible commodity, where “any unit is, by nature or usage of trade, the equivalent, of any other like unit.” R.C. 1301.01(Q); Wright Aeronautical Corp. v. Glander (1949), 151 Ohio St. 29, 42, 38 O.O. 510, 516, 84 N.E.2d 483, 489. Consequently, Ashland need only quantify an amount of oil that it cannot sell but every ten years.

Next, Ashland presents a plausible, argument to value the disputed oil. It could sell this oil only after it drained the tanks to maintain them; this occurred every ten years. Thus, finding the present worth of the oil might be appropriate. According to Johnson, Mini-Math for Appraisers (1974) 23-24:

“Present worth tables are predicated on the principle that a payment due at some future time is worth less today and must therefore be discounted. One dollar payable one year from today, including 6% interest, is not worth $1 today. Precisely it is worth $0.9433962264; practically, it is worth 94 cents.

“Present Worth of 1 factors frequently are referred to as the reversionary factors. They are used in the property reversion (residual) technique and in any valuation of a single terminal payment or worth. By use of the PW 1 factors one can value a single future income payment today, with rate, compounding interval, and time period given. A single ‘lump sum’ payment at a future date will return the original single capital investment plus accumulated compound interest, which is in reality deferred yield.” (Emphasis added.)

To its detriment, Ashland failed to take into account its staggered maintenance schedule. On each tax listing date, not all tanks "will be drained in exactly ten years for Ashland to have access to the oil to sell it. According to the testimony, Ashland drained the tanks on a staggered basis; thus, the holding periods as of each tax listing date varied. Therefore, to calculate Ashland’s inventory correctly, it needed to factor in the remaining holding period for each tank as of each specific tax listing date. Since the varied holding periods were not contained in the calculations, Ashland’s valuation evidence was not competent and probative to overcome the presumption in favor of the commissioner’s order.

Accordingly, we affirm the BTA’s decision because it is reasonable and lawful.

Decision affirmed.