We do reconciliations for over 100 accounts daily. These are very time consuming and I've used Match and Index, but the issue I'm having is that most of the time it takes a combination of values to equal one or a combination of other values from a different column to make a match. For example, column A will have 1200 and 800, and column B will have 1100 and 900. These two amounts when combined equal the sum of the other 2 amounts. Is there a formula that can check all possible combinations in one column and compare them with all combinations from the other column?

Try adding helper columns that sum the two columnns. Then use those for your matching...