Net IncomeFIFO = Net IncomeLIFO + (LIFO ReserveEnd − LIFO ReserveBeginning) × Marginal tax rate
The change in LIFO reserve (Δ LIFO reserve = LIFO ReserveEnd − LIFO ReserveBeginning) is, by definition, the difference between LIFO COGS and FIFO COGS for that period:
Δ LIFO reserve = COGSLIFO − COGSFIFO
– or –
COGSFIFO = COGSLIFO − Δ LIFO reserve
As you work your way down the income statement, no other line item changes (until taxes), so,