Due to payroll error, I didn't get paid for my first month and will get paid first month salary with second month. Does this mean I'm going to get hammered for tax?

No more than usual. You'll get taxed at the same rate.

possibly, but confirm with your HR department to make sure they calculate your tax for EACH month and not lump it all together this month. this 'fix' is extremely easy and legal to do from an employers point of view.

Well there is a possibility because i got my sal+ bonus together and unfortunately i was taxed more than the normal only sal rate... i guess i moved into a different tax bracket... check with your HR to avoid any surprises later..

that is exactly what happened in your case. you paid the 'correct' amount of tax for what you 'earned' that month whether you liked it or not! (c;
unless you can arrange for you employer to spread the bonus over several months you will see this one off massive tax hit.

for regular monthly salary, as i mentioned above, it is easy and legal for them to 'post date' the first calculation and then do the current month as usual. but the OP really should make sure with his HR.

not sure if its different, but im a expat, taxed at source and my monthly tax is cumulative.

eg.

to make things easier to understand assume you earn 120k and pay tax at 10 %in jan u earn 10k and get taxed 1k so net is 9kif they miss feb, and pay it all in march .then your cum march total is 30k and tax is 3k.take off what has already been taxed earlier, then u should get paid 20k-2k tax = 18k in march.same with bonus. If u get a bonus in april of 5 kthen your cum gross is 45k, and your tax should be 4.5k then less what has previously been paid. You should get 15k - 1.5k = 13.5k in april

this is my understanding after speaking with payroll. HR didnt help me to much. not sure if it changes depending on canton, i only been here for a few months

that's the strangest setup i've ever heard in CH and question if it is legal! my understanding is that you pay no tax at source, or you pay based on what you earn in a month using the official rates for your canton.

what do they do with the other deductions? state pension, company pension, insewerance etc

most of those are based on the monthly top line!