Bank statements are requested for visas, mortgages, personal loans, rental applications and university admissions. In every case the assessor is answering the same two questions, where does the money come from, and does the pattern support what you have claimed, and knowing that makes the requirements much easier to meet.
This is general guidance on what assessors look for. The specific requirements are set by the embassy, lender or landlord, and their published list is the one that counts.
How many months
The common asks: three months for most visitor visas and rental applications, six months for mortgages and larger personal loans, and six to twelve for student visas and self-employed applicants, who face more scrutiny because their income is less regular.
Send exactly what was asked for. Sending more looks like padding and gives the assessor more to query; sending less is the most common cause of a request for further information, which usually costs weeks.
What the assessor is actually reading
Regular income. They want to see money arriving on a predictable schedule from a recognisable source. A salary credited on the same date each month is the easiest thing to assess.
The closing balance, and how it got there. A large deposit shortly before the application is the single biggest trigger for questions. Assessors are looking for borrowed money temporarily parked to inflate a balance. If you did receive a legitimate lump sum, a bonus, a property sale, a gift, expect to be asked to evidence it, and prepare that before applying rather than after.
Whether the balance is sustained. Money that arrives, sits for a fortnight and leaves reads very differently from money that has been there throughout.
Commitments and outgoings. For lending especially, existing loan repayments and regular gambling transactions both count against you, and both are plainly visible in a statement.
The format mistakes that cause delays
Screenshots from a banking app. Almost universally rejected. They carry no bank identifiers and are trivially edited. Download the official PDF statement.
Redacted transactions. Blacking out entries you consider private reads as concealment. Assessors would rather see a complete statement.
Missing pages. Statements are numbered "page 2 of 7" for a reason, and a gap in the sequence gets queried every time. Send the complete document.
Statements that do not show your name and account number. Usually on the first page. A transaction list without them proves nothing about whose account it is.
A converted spreadsheet instead of the original. Send the bank's PDF as the evidence. A spreadsheet is a document you produced, and it carries none of the bank's formatting or identifiers.
Where converting to a spreadsheet does help
Not as the submission, as your own preparation. Before sending statements to anyone, it is worth being able to answer the questions they will ask.
With the statements in a spreadsheet you can sort by amount and find every large deposit in one pass, so nothing surprises you. You can total your monthly income to check it matches the figure on your application form, which is a discrepancy that causes real trouble. And you can total your regular commitments before a lender does it for you.
The converter here does this without the statements leaving your device, which matters when the whole exercise is about a document containing your account number, salary and address. It also verifies its own extraction against the running balance, so the figures you check against your application are the figures the bank printed, see how to check a converted statement.
A note on sending them
Use the organisation's own upload portal rather than email where you can; email keeps copies in several places indefinitely, on both sides. And be sceptical of anyone asking for statements outside a process you started, a request for bank statements is a common phishing lure precisely because it seems routine during a loan or rental application. More on the exposure in what you give away.