<form class="row" action="https://www.example.com" method="POST">
  <div class="col-12">
    <div class="col-12 form-group">
      <label for="exampleInputEmail1">Email address</label>
      <input type="email" class="form-control" id="exampleInputEmail1" aria-describedby="emailHelp" placeholder="Enter email">
      <small id="emailHelp" class="form-text text-muted">We'll never share your email with anyone else.</small>
    </div>
    <div class="col-12 form-group">
      <label for="exampleInputPassword1">Password</label>
      <input type="password" class="form-control" id="exampleInputPassword1" placeholder="Password">
    </div>
    <div class="col-12 form-group form-check tncWrapper">
      <label class="form-check-label" for="exampleCheck1">I accept the <a id="tncLink" href="https://www.example.com">terms and conditions</a></label>
      <input type="checkbox" id="tncCheckBox" id="exampleCheck1">
    </div>
    <div class="col-12">
      <button type="submit" class="btn btn-primary">Submit</button>
    </div>
  </div>
</form>

body {
  margin-top: 100px;
}

.tncWrapper {
  display: flex;
}

#tncCheckBox {
  order: -1;
  position: relative;
  top: 4px;
  margin-right: 5px;
}