Cleaning companies have simple books if the categories are right from the start. These six cover nearly every line.
The drive from one client to the next is the record most cleaning companies lose. Log each job's miles the same day; monthly totals come from that, not from a guess in April.
Weekly and biweekly clients should be invoiced on a schedule and the payments matched to the invoice, so "who still owes me" is a one-line answer.
We keep a cleaning company's books ourselves, so this is the setup we start new cleaning clients with.
Flat monthly price, quoted on a 20-minute call.