Every mortgage lender runs a credit check when you apply. What they see on your credit report, combined with their own internal scoring models, determines whether you are approved and at what rate. Understanding this process gives you a significant advantage.\n\nThe Three Credit Reference Agencies — The UK has three main agencies: Experian, Equifax, and TransUnion (formerly CallCredit). Each holds slightly different information because not all creditors report to all three. Before applying for a mortgage, check all three. You have a legal right to see your statutory credit report from each agency for free. Experian offers this through its free tier. Equifax offers free access through ClearScore. TransUnion offers free access through Credit Karma. Check all three at least three months before your mortgage application.\n\nWhat Lenders Actually See — Your report contains your name, date of birth, and address history for the last six years. It shows every credit account you have held including credit cards, loans, overdrafts, mobile phone contracts, and car finance. For each account it records the credit limit or loan amount, the current balance, your monthly payment history going back six years, whether the account is active or closed, and any missed or late payments. It also shows any County Court Judgments, bankruptcy, IVAs, or debt management plans. It lists every credit application you have made (the searches section). And it shows your electoral roll registration, which is used to verify your identity and address.\n\nCredit Scores vs Lender Decisions — Experian, Equifax, and TransUnion each give you a credit score. These scores are marketing tools created by the agencies — they are not used by mortgage lenders. Lenders have their own internal scoring models that weight factors differently. A perfect Experian score does not guarantee a mortgage. A mediocre score does not prevent one. What matters is the underlying data, not the number. That said, if something is dragging your score down, it is probably something a lender would also view negatively.\n\nWhat Hurts Your Application — Missed or late payments are the most damaging items. Even one missed payment in the last 12 months can limit you to specialist lenders at higher rates. Defaults and CCJs remain on your report for six years and severely restrict options. High utilisation of credit limits is a red flag — using 90% of a 5,000 credit card limit looks worse than using 20% of a 20,000 limit, even though the actual debt is similar. Multiple credit applications in a short period suggest financial stress. Payday loans, even if repaid on time, are viewed negatively by almost all mainstream lenders. Being on a debt management plan or IVA is a significant barrier for most lenders.\n\nWhat Does Not Hurt Your Application — Checking your own credit report has zero impact. Student loan debt does not appear on your credit report (though lenders factor the repayment into affordability). Being declined for credit does not show on your report — only the search appears. Having no credit history is not necessarily bad, but it makes it harder for lenders to assess you. Savings account balances do not appear. Your salary does not appear.\n\nFixing Errors — Credit report errors are more common than you might think. Accounts that are not yours, incorrect addresses, closed accounts showing as open, and wrong payment statuses all occur. If you find an error, raise a dispute with the relevant agency. They have 28 days to investigate and correct it. If the dispute is upheld, the correction is made within days. If the creditor disagrees, you can add a Notice of Correction — a 200-word statement explaining the circumstances that lenders must consider.\n\nImproving Your Report Before Applying — Register on the electoral roll at your current address (this alone can significantly improve your position). Pay down credit card balances to below 30% of the limit. Do not apply for any new credit in the three to six months before your mortgage application. Do not close old credit accounts — long-standing well-managed accounts help. Set up direct debits for every credit commitment to avoid accidental missed payments. If you have thin credit history, a small credit card used for regular spending and paid in full each month builds a track record quickly.\n\nThe Timing of Searches — When you apply for a mortgage, the lender performs a hard search that other lenders can see. Multiple hard searches in a short window can look concerning. However, mortgage searches within a 30 to 45 day window are typically treated as rate shopping and counted as a single search. This means you can apply to multiple lenders through a broker without damaging your report, provided it is done within a concentrated period.\n\nAddresses and Financial Links — Your report links you financially to anyone you share a credit product with — a joint bank account, joint mortgage, or joint loan. If that person has a poor credit history, their issues can affect your application. If you have financial links to someone with problems, close any joint accounts and apply to the agencies to have the financial association removed. This takes a few weeks but can make a material difference.