I don't think that's okay. Any reasonable expenses you incur when asked to work from home should be submitted as a paid expense. Others have mentioned overtime,

I don't think that's okay. Any reasonable expenses you incur when asked to work from home should be submitted as a paid expense. Others have mentioned overtime, which you are entitled to if you are paid hourly. If paid as a salary, then in my experience the general arrangement is time off for extra hours worked, whether that's a formal process or simply cutting out a couple hours early on a Friday if you put in a couple hours extra during the week.