T5 split percentage doesn't seem to update properly

[EW4]

I enter a T5 and put 50% for me and enter it again under my spouse and enter 50% there too.  

The 50% for me adds $500 to what we owe.  When I enter the 50% for my spouse it then adds another $500.  If I delete one and just make it 100% for one of us the total we owe for it is $550 instead of the $1000 when I split it.  Why is that?

thanks.

[EW4 · Accepted solution]

I see what's happening.  You can ignore my post above but I think I need to check my filings for prior years as might have over paid.  When you enter a percentage it automatically splits the amount between the partners although when I use the forms method I don't see the split but the math seems to work that way.