Screening a voucher applicant: same income test, or lean on references instead?

First rental closes in three weeks and I've been writing my screening criteria down so I apply the same ones to everybody. The income rule I drafted is three times the rent in verifiable income. Then I got to the voucher section and it stopped making sense.

If the rent is 1,300 and the authority pays 1,000 of it, the applicant's obligation is 300. Testing them against 3,900 of income when they owe 300 seems like it screens out people who would pay fine, and in a number of states and cities source of income is a protected class, so how you apply an income test to a voucher holder can create legal exposure. That's a question for a lawyer licensed where the property is, and I plan to ask one.

Setting the legal piece aside, there's a real judgment call underneath. Do you apply the income multiple to the tenant's portion only, drop the income test for voucher applicants and weight landlord references and payment history harder, or keep one identical standard for everyone on the theory that consistency is the safest defense?

I can argue all three. The references version feels like the most accurate predictor of whether that 300 shows up every month. The identical standard version feels like the easiest thing to explain if anyone ever asks me why I chose one applicant over another. And the tenant-portion version is the one that actually matches the obligation.

Where does the room land?