I know SMP is 136.78 but am trying to figure out what take home will be monthly after tax. I did all the calculations on the HMRC website but am presuming the SMP calculations it gives me are gross and not net. If I am in a standard tax band does anyone know what £586 smp in a month would be in take home? Am very confused! the site has it fluctuating monthly between £605-566 depending on the month but need to figure out the percentage I am deducting to make sure my take home calculations are correct. Sorry to be confused!