Tax Deferral question from mock carrying, question, liability, 2010, accounting

towardsutopia21

One of the CFA mocks has a question about the tax deferred liability at the end of 2010...

.....for accounting purposes, the carrying values are 2010: 1800, 2009: 1900.
for tax purposes, the bases are: 2010: 1280, 2009: 1600.

The tax rate droppped to 25%. My understanding is that the DTL would be (1900-1600)*.25+ (1800-1280)*.25 = 205. However, the answer is just (1800-1280)*.25 = 130. Why does the CFA no account for the change in the previous year's DTL?

MythosHF

I believe its because the 2010 values already contain the 2009 values, because its cumulative..... but I may be wrong.....