Online Calculators since 2009
Below are a few do’s and don’ts when it comes to completing your Self-Assessment Tax Return (SATR). As always this is just a guide so you must always check you individual circumstances against any advice given.
Do get yourself registered for the self-assessment system as soon as possible. You'll need a Unique Taxpayer Reference Number (UTR), and they'll only send it by post. It can take at least 10 days; so don't end up missing a deadline just because HMRC's hasn’t sent it in time. You'll also need an account and activation code for the Government Gateway site if you want to file online.
Don’t enter a postcode when requested if you live abroad – the system does not accept foreign postcodes. The field is not compulsory so you will be able to leave it blank and fill in the rest.
Do quote your "unique taxpayer reference" (UTR) on your tax return – it is 10 digits long and can be found on various bits of paperwork from HMRC. If you don't know what it is, you need to get in touch and request it – you won't be given it over the phone and will have to wait for it to arrive by post.
Don't confuse your UTR with your national insurance number. Sometimes HMRC puts your NI number [which is always in the format AA 12 34 56 B] in the 'tax reference' field on your Notice to Complete a Tax Return. Don't make the same mistake – put in your UTR when asked for your tax reference number."
Don’t ignore the deadlines or assume it's okay to be a few days late. If you reach February and still haven't filed your return, you'll be issued with a £100 fine. Don't leave it too late.
Do let the taxman know if you've got a genuine reason for missing the deadline. If it's really not your fault, he might give you a little room to get the information submitted. Don't count on catching him in a forgiving mood and make sure your excuse is a good one and legitimate.
Don’t assume that you've been asked to submit a tax return by mistake. It can happen, but ignoring the demand just because it's unexpected is always a mistake. If you can prove you don't need to file a return, HMRC will back off. Until you do, though, they'll be expecting your paperwork on time.
Don’t worry if you already have a self-assessment online account but have lost your user ID and password. You can now request replacement credentials via the HMRC website.
Do file your self-assessment return even if you know you won't owe any tax this year. It doesn't matter how little you earned, the taxman still needs you to submit you self-assessment tax return.
Don’t assume that HMRC doesn't care about your online sales side hobby. If you're doing enough of it they can call it a business and expect a self-assessment tax return from you.
DO remember to file your self-assessment return, even if your business is no longer trading this year. You need to make sure your books are up to date until the very last day you were trading.
Don’t think you can skip over the self-assessment pages about renting out property just because you make a loss on it. Whether you're up or down on the deal, you've got to account for the money.
Don’t assume you have submitted your tax return when you haven't. Reaching the calculation page does not mean you have submitted your return. HMRC says people sometimes think at this point that they are finished. In fact, you have to keep going until you have re-entered your user ID and password.