Can I afford to take a 4 day week

I currently work 5 days a week and am considering applying for a 4 day week. My current salary is 50K. If I take the 4 day week that will reduce my monthly salary by 20%. However, given that I will be taking home less pay I imagine I wouldn't be paying as much tax. How do I calculate the net effect of me taking a 4 day week ?
Thanks

You can check this by downloading my Excel spreadsheet at http://taxcalc.eu/monthlyss

If you need a hand with using it feel free to leave a message here or use the email on the sheet itself.

Thanks - I'll take a look at this

Hi Deadly Duck,
I tried it but it wouldnt work for me.

Hi NewRoss,

Did the spreadsheet download correctly or was it a 'mess' of weird looking XML files? If the latter, see here for the download procedure (this sometimes happens in Internet Explorer).

If it downloaded and opened OK but you could only see a 'Macro warning screen', then you need to enable macros in your version of Excel- the text on that screen should give instructions or you can click the hyperlinks visible at the botom of the screen.

Plan C- PM me your details and I can either email a working copy to you (approx 2.7Mb in Excel 2007 format, much bigger in Excel 2003, so there may be email size limitations) or run your values through it and I can reply with answers.