Rule 4-213 Alimony.

When a court decides child support and alimony together, child support comes first. The judge figures out how much child support one parent owes, and only after that amount is set does the court look at spousal support (alimony).

This means alimony is based on whatever income is left over after child support payments are accounted for. The parent who pays child support won't have that money counted twice, once for child support and again for alimony. Instead, the court looks at what money remains available once the child support obligation is already factored in, and uses that to decide alimony.