I reside in UK and I am full time employee. I came across a job that bases new employees salary on the old one. I also have been told that I will have my credit checked if I were made an offer. The question is - can a new employer know of my financial dealings without me giving them out voluntarily?
You do not have to give them your previous salary information, nor do you have to consent to a credit check. However, they may choose not to offer you a position if you refuse to co-operate with them. There is no point in lying as they will find out from your P45 or HMRC (as Macro Man explains). That being said, you might get away with it if you time your job move for early April (new tax year) and don't supply your P45 to your new employer.
Credit checks will only provide limited information to your new employer. They won't have access to your bank account transactions for example. Typically I understand they will only have access to limited information (verifying address and if you have any CCJ's, which are public record anyway). However, that will depend on the role - if you need in-depth vetting for government work for example, you can assume they will go much further.
The Experian website, which is one of the three big UK agencies, gives details of the sort of information they will release.
Yes, and.... No.
When you start a new job, you will need to submit your P45 from your previous employer (even if you don't, they eventually get this information from the revenue electronically) - this has your taxable YTD earnings which doesn't tell them exactly what you earned but gives them a rough idea. (If you say you earn £50,000 and your Taxable Pay YTD is £15,000 in March then chances are something isn't quite right...)
UK Employers have a statutory obligation to report all earnings via RTI (Real Time Information) to HMRC, but again this doesn't actually state your salary - just taxable earnings and earnings that qualify towards things like pensions and benefits.
Bottom line - an employer cannot gain access to any PII (Personally Identifiable Information) from anywhere without your explicit consent to either them, or the supplier of the information. If they do - then they are potentially in breach of the Data Protection Act and leave themselves wide open to legal action.