The high-calibre small-cap stock flying under the City’s radar Our 6 ‘Best Buys Now’ Shares My best Stocks and Shares ISA investments for 2021 and beyond Click here to claim your copy of this special investment report — and we’ll tell you the name of this Top Small-Cap Stock… free of charge! Renowned stock-picker Mark Rogers and his analyst team at The Motley Fool UK have named 6 shares that they believe UK investors should consider buying NOW.So if you’re looking for more stock ideas to try and best position your portfolio today, then it might be a good day for you. Because we’re offering a full 33% off your first year of membership to our flagship share-tipping service, backed by our ‘no quibbles’ 30-day subscription fee refund guarantee. Simply click below to discover how you can take advantage of this. The end of the tax year is rapidly approaching, which means investors are running out of time to use their ISA allowance for the year. With that in mind, I’ve recently been seeking out the best Stocks and Shares ISA investments for 2021 and beyond to add to my portfolio. Best Stocks and Shares ISA investmentsDue to the tax-efficient nature of ISAs, I believe they’re more suitable for holding some investments than others.5G is here – and shares of this ‘sleeping giant’ could be a great way for you to potentially profit!According to one leading industry firm, the 5G boom could create a global industry worth US$12.3 TRILLION out of thin air…And if you click here we’ll show you something that could be key to unlocking 5G’s full potential…Any income or capital gains earned on investments held inside an ISA wrapper doesn’t attract any tax liabilities. This can be especially helpful for higher rate taxpayers, although it will vary from person to person. When considering tax obligations, there’s never a one-size-fits-all solution. Still, I believe that the best Stocks and Shares ISA investments are those companies that can generate capital growth and produce a steady income stream over the long term. I want to focus on companies that I know well and produce products with a substantial consumer following. These include organisations such as AG Barr and Britvic. The former manufactures and sells the Irn-Bru brand. While the latter owns the rights to the Robinsons and Fruit Shoot brands, among others. Britvic also holds a Royal Warrant, which means it’s the fruit juice and soft drinks supplier of choice to the Royal Households.These companies do face challenges though. The sugar tax and uncontrollable ingredient costs have hurt profit margins.However, I think they’ve plenty of opportunities as well. The UK soft drinks market is expected to grow by around 2.5% per annum every year for the next five years. AG Barr and Britvic should be able to capitalise on this growth.The groups also have a good record of returning cash to investors through share buybacks and dividends when profits are high. There’s no guarantee this trend will continue, but I think it showcases both companies’ desire to reward investors. These are some of the reasons why I believe they’re the best Stocks and Shares ISA investments for 2021 and beyond. That’s why I’d add them to my portfolio today.Market leader I’d also buy financial services group IG for my ISA before the end of the tax year. This company, which started out as a spread betting provider, has expanded rapidly over the past few years into areas such as stockbroking. It’s now expanding overseas. The organisation recently announced a large deal that will significantly expand its presence in the US. As the company continues to invest in growth, I think it could produce large capital returns. However, this is far from guaranteed. In the highly controlled financial services industry, regulators can dictate the success or failure of a corporation overnight. That has happened to IG in the past. Regulators banned the selling of highly leveraged trading products to retail investors several years ago, and the firm’s sales plunged. Despite these risks, I’d buy the stock for my portfolio today. As IG builds its brand across the world, I reckon the business is only just getting started. See all posts by Rupert Hargreaves Adventurous investors like you won’t want to miss out on what could be a truly astonishing opportunity…You see, over the past three years, this AIM-listed company has been quietly powering ahead… rewarding its shareholders with generous share price growth thanks to a carefully orchestrated ‘buy and build’ strategy.And with a first-class management team at the helm, a proven, well-executed business model, plus market-leading positions in high-margin, niche products… our analysts believe there’s still plenty more potential growth in the pipeline.Here’s your chance to discover exactly what has got our Motley Fool UK investment team all hot-under-the-collar about this tiny £350+ million enterprise… inside a specially prepared free investment report.But here’s the really exciting part… right now, we believe many UK investors have quite simply never heard of this company before! Enter Your Email Address Image source: Getty Images Rupert Hargreaves | Saturday, 6th March, 2021 | More on: BAG BVIC IGG Rupert Hargreaves owns no share mentioned. The Motley Fool UK has recommended AG Barr and Britvic. Views expressed on the companies mentioned in this article are those of the writer and therefore may differ from the official recommendations we make in our subscription services such as Share Advisor, Hidden Winners and Pro. Here at The Motley Fool we believe that considering a diverse range of insights makes us better investors. I would like to receive emails from you about product information and offers from The Fool and its business partners. Each of these emails will provide a link to unsubscribe from future emails. More information about how The Fool collects, stores, and handles personal data is available in its Privacy Statement.