If we hire a new employee, we need him to provide us P45 form or P46 form. In how many days this should be submitted to HMRC.
ASAP as you may get a new code for him.
And when we move to RTI next year it will have to be submitted immediately they start.
That is correct by the HMRC book. In practice I usually wait a month or two for P46s, as all too often it turns out - despite the fact that I have a customised P46 form for client staff to read explaining what each box means - that they've ticked the wrong box.
Now if HMRC were efficient and reliable I would not wait. Back in the real world, you normally find out within 2 pay runs if the new staff person thinks they are on the wrong code. If after discussion I agree, I change the code and then submit the P46 with the code we are all happy with.
Likewise, when someone leaves you only get one shot at the P45, no resubmission option. So I wait at least one or two payment runs before submission. This has saved me loads of hassle many times when it turns out that either client or employee has queried the final payslip.
Again I stress that if you could rely on HMRC putting right these minor errors quickly at the first bite of the cherry without my having to listen to music I don't much like for ages, or explain myself over and over again to different people, or write letters which don't get read for weeks, I'd follow the book.
Back in the real world one of my KPIs is to minimise all contact with HMRC, and only call or write to them as a last resort. Hence the delay on P46 and P45.
One possible mistake is recognised by HMRC. They do not want the joining P45 or P46 submitted until the first payroll including the new employee is run. The intention is to avoid new employees who never actually turn up to work.
Apart from that, I think Mr Mischief is being unduly cautious. His approach of waiting for two payroll runs the risk of forgetting to submit the forms at all. It is far easier to do it as part of the first payroll run for new starters. I find that HMRC are pretty good at coming back with a different PAYE code if appropriate, sometimes as quickly as the day after submission.
With regard to leavers, we always double check with the client first to see if there is any unpaid holiday or other payments to be included, but we then submit the leaving P45 when we have run the leaver's final payroll, again for the certainty of knowing that we have not forgotten to file the form. Very rarely, the client comes back and says that some payment has been omitted, in which case the official procedure is simply to process the additional payment on code 0T - no further P45 is issued, but the additional payment is included on the end of year P14. Even more rarely, the client comes back and says they have told us to pay too much and in those very rare circumstances, I am prepared to write to the PAYE district to amend the P45.