Proof of tenant's earnings

Rent Arrears

Hello all, I am looking for some advice regarding checking if our tenant can now afford to pay his rent. When the lockdown started in March he was furloughed - he depends on commission to boost his earnings, so the furloughed wage only consisted of 80% of his take home wage. We agreed to take the hit at the time, and avoid him getting stressed about rising debts and dropped his rent by £200 / month, to £250 / month, as a temporary agreement, until he went back to work. That was in March, he was back in work in August, but has not yet resumed full rent payments. He hasn't said anything about his commission/earnings not returning to pre-Covid levels. He had previously always paid his rent on time.

My question is, am I entitled to request sight of his payslips, from the last couple of months, and pre-Covid, as we are beginning to feel that he is taking advantage of the situation.

Any advice/thoughts are very welcome.

Thank you in advance!