Spouse visa Extension-FLR (M) Salary per month question

Dear All,
I want to apply for extension of visa for my wife. Would you like to advise me about financial requirement. I know it is 18600 per year. My question is, does home office require exact earning of 1550 per month either it can be less in one month and more in other months than this amount or the total during last 6 months or 1year.
Best regards.
Tariq

If the monthly earnings are variable, the Case Worker will take the lowest month and multiply it by 12 to calculate the annual income.

It all depend whether you are applying under salaried or non salaried employment

Salaried employment of category A : They take lowest monthly earning from last 6 months and multiply it with 12 to see whether you make £18600

Non salaried of Category A: They add up last 6 months earning which is often variables and then divide it by 6 and multiply with 12 to see whether you meet the requirements

Keep in mind as well that any overtime, bonuses, etc (so long as clearly labelled on the payslip), are added to your salary in the form of non-salaried income. I suggest checking out sections 5.5.7, 5.5.9, and 5.5.24.