Paper is the one category where people keep far too much and still cannot find the thing they need. The cause is filing by document type rather than by what you would be looking for, and the cure is fewer categories than feels safe.
Four categories are enough
Most households need: property and vehicles, money and tax, health and identity, and a single current folder for anything live. Insurance schedules go under the thing they insure, not under insurance. The test for any category is whether, in a hurry, you would know which one to open. If you would have to think, you have too many.
One place for incoming post
The pile that grows on the hall table is not a filing failure, it is a missing step. Put one tray or box where the post lands and let everything go in there unopened if necessary. The point is that it is contained and in one place, so the weekly ten minutes of dealing with it is a known job rather than a hunt through three rooms.
How long to keep things
Utility bills and bank statements are worth a year unless they support a tax return or a warranty claim, in which case they follow the longer period for that. Anything tax-related wants several years, and the exact number depends on where you live and whether you are self-employed, so check the current guidance for your own situation rather than relying on a number in an article. Guarantees and receipts for anything expensive are kept for as long as the cover lasts, and the receipt matters more than the guarantee card. Property deeds, certificates and anything proving identity are permanent and belong somewhere you would grab in a hurry.
Scan the long-term, bin the rest
A photograph of a receipt is accepted by most retailers and every insurer worth having, and it takes seconds. Scanning everything is a project that never finishes, so scan only the things you would be upset to lose, and let the rest go on paper with a date on the folder.
Shredding
Anything with an account number, a signature or a date of birth is worth shredding rather than binning. That is a smaller pile than most people assume, and treating it as a small pile rather than everything is what makes it actually happen.
The annual pass
Once a year, take out the oldest year's folder, pull anything still live, and recycle the remainder. Ten minutes, and it is the only thing standing between a working system and four boxes in the loft that nobody will ever open.