How will child support and alimony affect mortgage qualification?

It depends if you are the person receiving these support payments or if you are the person paying these support payments.

If you receive support and/or alimony - generally the amount you receive can be added to your total income, provided proof of regular receipt is available (e.g., court ordered payments, banking history showing deposits of the payments, or a separation agreement that specifies the support arrangements).

If you pay child support and/or alimony, generally the amount you pay must be deducted from your total income before determining the size of mortgage you will qualify for.