Currently rolling windows support HOURLY, DAILY, WEEKLY. Being able to add MONTHLY would be very helpful for the customers using union agreement rules such as Max X hours in 4 months, Min X hours in 4 months. If we're using periodRules for "MONTH" and dividing X with 4, this removes the flexibility of being able to work a lot of hours in a single month, and a few in the next. In theory it would probably work with a rollingWindowRules type: "DAILY" and size: "amount of calendar days in 4 months" however, this would be cumbersome as the amount of days in a month varies. There might be another way to solve this, but here is an example of what I suggest: The employee can work a maximum of 400 hours in 4 months { "contracts": [ { "id": "fullTimeContract", "rollingWindowRules": [ { "id": "max24000MinutesRollingWindow", "rollingWindow": { "type": "MONTHLY", "size": 4 }, "minutesWorkedLimit": { "minutesWorkedMax": 24000 }, "satisfiability": "REQUIRED" } ] } ] } The rules are looking at rolling windows, and defined by calendar month. ----- CONTEXT ----- Let's say we're allocating a 4 month schedule starting April 1st, and we're sending historic data as pinned shifts. From January 1st to March 31st the employee has had 300 hours of work. This means the employee can work a maximum of 100 hours in April. From February 1st to March 31st the employee has worked 100 hours. This means the employee can work a maximum of 200 hours in May (assuming the employee got 100 hours allocated in April)